Provide a link to the person who made this classification and where you can read more about it — Astorre

As a start, there is the SEP article on Idealism and the SEP article on Realism.

Right, but these are peculiar forms of Idealism. — Joshs

Yes, Idealism is an extensive topic, as the SEP article on Idealism indicates.

Heidegger has "Being-in-the-World", but this may be a similar problem with Wittgenstein and the world. Where does this world exist, within the mind (Idealism) or external to the mind (Realism). Wittgenstein never says.

As the Wikipedia article on Ontology notes:

According to philosopher Rudolf Carnap, for example, ontological statements are relative to language and depend on the ontological framework of the speaker. This means that there are no framework-independent ontological facts since different frameworks provide different views while there is no objectively right or wrong framework

First of all, I want to say that I was not impressed by the approach of the author you cited. "Realism vs. idealism” in their presentation is a mixture of ontology and epistemology, while phenomenology and existentialism, in principle, work on a different plane.In my opinion, this classification of ontological approaches was obviously carried out by the author for educational purposes. For me, as the author of the topic, it does not matter where the lovers of classification will place me. Creating something new is a process of going beyond any existing classifications, at least I want to believe in it.

As for your comments:

Husserl's phenomenology is certainly that of ontological idealism, where any belief in the world's independent existence is put aside to focus on human experiences. — RussellA

Heidegger's Dasein is also about ontological Idealism. It is about "being-in-the-world", in that we are not detached observers of the world but embedded in our experiences. — RussellA

The text you provided says:

...Although insofar as Neo-Kantianism was a reaction mainly to absolute idealism it could not entirely reject epistemological arguments of the kind that had traditionally led to idealism, especially in its Kantian variety. Hence idealistic tendencies can be found in Neo-Kantianism too, and Martin Heidegger’s later version of realism can be interpreted as a response to the idealism in Neo-Kantianism....

....In so-called “continental” philosophy, we might suggest, the main alternative to the idealism of the nineteenth century and lingering tendencies to idealism in both Neo-Kantianism and Husserlian phenomenology has not been any straightforward form of realism, but rather the “life philosophy” (Lebensphilosophie) pioneered by Wilhelm Dilthey (1833–1916), then extensively developed by Martin Heidegger (1889–1976), and, without Heidegger’s political baggage, by the French philosopher Maurice Merleau-Ponty (1908–1961).... https://plato.stanford.edu/entries/idealism/

In my opinion, this is written quite accurately and agrees with the comment:

Heidegger’s Idealism puts into question the priority of mind, reason and consciousness, associating all of these with the Cartesian subject, which is still operative in Kant and Hegel. Dasein is more radically in the world than any notion of a conscious subjectivity perceiving objects can convey. — Joshs

In my opinion, we have gone too far, wandering in all sorts of classifications or approaches. Before you is the text of my work. Did you like it or not like it? What do you agree or disagree with? Destroy my arguments or approve them. My text is here precisely for this

In my opinion, we have gone too far, wandering in all sorts of classifications or approaches. — Astorre

Yes, fixing one's definitions adds complexity to an already complicated topic, such as establishing the differences between being and becoming, ontology and epistemology, realism and idealism, static and dynamic, substance and process, presence and absence, mind and world.

Even if we agreed that "Dasein is more radically in the world" we may not agree as to where this world is. Does this world exist within the mind or external to the mind? Is our world the construction of our mind. As Schopenhauer wrote "The world is my representation". As Abai Qunanbaiuly wrote “A person’s mind is the mirror of the world. If the mirror is clouded, the world appears distorted.” Wittgenstein avoided such a problem by never giving his opinion where his "world" exists. A strategic decision that does not seem to have affected his reputation.

As you say "And since philosophy speaks about the world relying solely on language, this creates difficulties for both the researcher and the reader."

I will try to be more specific to your text.

Does this world exist within the mind or external to the mind? Is our world the construction of our mind. As Schopenhauer wrote "The world is my representation". As Abai Qunanbaiuly wrote “A person’s mind is the mirror of the world. If the mirror is clouded, the world appears distorted.” Wittgenstein avoided such a problem by never giving his opinion where his "world" exists. A strategic decision that does not seem to have affected his reputation — RussellA

Is it that he never gave his opinion, or that his answer is implicit in his later work, but has been missed by many because they are still looking for answers within the old binary:either mind or world, either inside or outside? Merleau-Ponty directs us to this way beyond the inside-outside trap:

” “[t]he world is inseparable from the subject, but from a subject who is nothing but a project of the world; and the subject is inseparable from the world, but from a world that it itself projects.” (Phenomenology of Perception)

Even if we agreed that "Dasein is more radically in the world" we may not agree as to where this world is. Does this world exist within the mind or external to the mind? Is our world the construction of our mind.

Perhaps what these people are talking about is always skirting around the edge of the truth of the matter. Whenever one takes aim, the attempt glances of in a tangent and never reaches the target. This would suggest a return, or synthesis with, the alternative approach of the East. The apophatic, or realisation of the route of stillness.
If one is not addressing the target, or not addressing that which always misses the target, one is not wrong. Not as wrong as the person who addresses it, but misses.

Is it that he never gave his opinion, or that his answer is implicit in his later work, but has been missed by many because they are still looking for answers within the old binary: either mind or world, either inside or outside? — Joshs

I cannot accept that there are no binaries, and everything is a formless soup of amorphousness.

I cannot accept that Tyrannosaurus rex did not have an existence outside the human mind, a real, living and breathing existence outside of our concept of it.

I cannot accept that there is no binary between the mind and a mind-independent world, even if I accept that discovering it is philosophically difficult.

I cannot accept that there are no binaries, and everything is a formless soup of amorphousness.

I cannot accept that Tyrannosaurus rex did not have an existence outside the human mind, a real, living and breathing existence outside of our concept of it.

I cannot accept that there is no binary between the mind and a mind-independent world, even if I accept that discovering it is philosophically difficult. — RussellA

The issue isn’t whether the dinosaur existed before humans. It’s that the meaning of ‘T. rex’, it’s place in our world, is a product of our engagement now. That’s the intertwining I’m pointing to. Empirical knowledge is not a passive representing of what’s out there. Discovering the world always also involves inventing new ways of doing things with it. As Evan Thompson wrote:

I would give up both realism and anti-realism, then, in favour of what could be called a pluralist pragmatism. What the pluralist insists on is that there is no foundational version, one which anchors all the rest or to which all others can be reduced. The pragmatist insists that the world is both found and made: it is made in the finding and found in the making. To erase the boundary between knowing a language and knowing our way in the world gives us a fresh appreciation of the world. That world, however, is not given, waiting to be represented. We find the world, but only in the many incommensurable cognitive domains we devise in our attempt to know our way around. The task of the philosopher is not to extract a common conceptual scheme from these myriad domains and to determine its faithfulness to some uncorrupted reality; it is, rather, to learn to navigate among the domains, and so to clarify their concerns in relation to each other.

The issue isn’t whether the dinosaur existed before humans. It’s that the meaning of ‘T. rex’, it’s place in our world, is a product of our engagement now. That’s the intertwining I’m pointing to. Empirical knowledge is not a passive representing of what’s out there. — Joshs

Introduction
As a supporter of Kant's Critique of Pure Reason, I agree that "Empirical knowledge is not a passive representing of what’s out there."

I also agree with Enactivism, the idea that the human brain has evolved in synergy with its environment (Wikipedia - Enactivism)

I am also an Indirect Realist, in that I don't believe that I experience the external world as it really is, but only through representations of how the external world really is.

It follows that I believe in Realism, in that there is a realty that exists independently of the mind.

It also follows that I believe in Anti-Realism, the idea that what we perceive as the world is dependent upon and has been constructed by our minds, whether in language or concept.

Therefore, believing in both Realism and Anti-Realism, my approach is similar to the pragmatism as described by Evan Thompson, who wrote that "the world is both found and made: it is made in the finding and found in the making". In the terms of Kant's Transcendental Idealism, the world is found in Realism, in his belief that a world exists independently of the mind, and the world is made in Idealism, through a priori pure intuitions of space and time and a priori pure concepts of understanding.

Heidegger's "Being-in-the-World"
The story goes back to Heidegger's "Being-in-the-World", a statement that I have no trouble with. My question is, where does this world exist, something Wittgenstein avoided engaging with.

There are two worlds, the world as we perceive it and the world that has caused the world we perceive.

The world we perceive is a representation of the world that has caused the world we perceive, not a mirror image.

We perceive the colour red even though the colour red does not exist in a mind-independent world. However, there must be something in a mind-independent world that has caused us to perceive the colour red. This something in a mind-independent world may be different to what we perceive, but it would be invalid to argue that because it is different it cannot exist.

Heidegger's "Being-in-the-World" agrees with our everyday experiences, but ignores the obvious question. Does "world" refer to the world as we perceive it to be or does "world" refer to a world that has caused the world we perceive.

Something has caused the world we perceive, and even though it may be very different to the world we actually perceive, whatever it is, it is still a world.

To ignore this fundamental question, what caused the world we perceive, as Wittgenstein did, may be pragmatic, but not very philosophical.

I cannot accept that Tyrannosaurus rex did not have an existence outside the human mind, a real, living and breathing existence outside of our concept of it.

Think about it like this. If life had not evolved at all on earth, today the planet would be just rock and sand with sterile oceans. There would not have been a T Rex. The existence of TRex is as a result of the endeavours of life, living organisms. Same with Sartre.
So everything in our world except for rock, water and gas, was created by our cousins and ancestors. Their minds literally created/caused these things.

So everything in our world except for rock, water and gas, was created by our cousins and ancestors. Their minds literally created/caused these things. — Punshhh

The first living organisms on Earth were bacteria, which had no minds, so It cannot be that life was created by the mind.

The first living organisms on Earth were one-celled organisms known as prokaryotes, which emerged between 3.5 and 4.1 billion years ago.
https://www.naturalhistory.si.edu/education/teaching-resources/life-science/early-life-earth-animal-origins

The first living organisms on Earth were bacteria, which had no minds, so It cannot be that life was created by the mind.

Well maybe we need to look at our definition of mind again. Because there was some kind of intelligence going on. An intelligent and strategic response to the environment of these single cell organisms, which led to the T Rex and Sartre.

An intelligent and strategic response to the environment of these single cell organisms, which led to the T Rex and Sartre. — Punshhh

That's certainly true. The real genius of Darwin was that he managed to create or identify a purely causal, unthinking system which achieved the results of an intelligent system. There's no need to posit any minds - unless you want to include them for other reasons than explaining the phenomena.

There's no need to posit any minds - unless you want to include them for other reasons than explaining the phenomena.

Not minds in the usual sense of the word. But an agency, which wouldn’t be present if there were no life at all. Even with natural selection there wouldn’t have been a T Rex without that agency.
I accept that the effect of natural selection played a formative role in this process. But so too did the living entities and their capacity to develop along with the resultant effects.

It was a dance so to speak, these organisms found the world and somehow were able to alter it and themselves to their benefit. While the world somehow lead them (shaped them) on an evolutionary path.

Both the organisms and the world as they found it were necessary for this lineage to happen.

Not minds in the usual sense of the word. But an agency, — Punshhh

Would that, perhaps, be the sort of agency that has enabled us to warm the climate and devastate much of the world?

Yes, but the lineage hasn’t finished yet. Who knows where it will go in the future.
Although, when it comes to the devastation of the planet, that turn of events happened when we had used intellect to subvert natural selection. Become too big for our boots.

Both the organisms and the world as they found it were necessary for this lineage to happen. — Punshhh

Absolutely.

Although, when it comes to the devastation of the planet, that turn of events happened when we had used intellect to subvert natural selection. — Punshhh

It seems to be true. Though one could also argue that the ability to do that was conferred by evolution and it looks as if the planet is taking action to restore balance.

The task of the philosopher is not to extract a common conceptual scheme from these myriad domains and to determine its faithfulness to some uncorrupted reality; it is, rather, to learn to navigate among the domains, and so to clarify their concerns in relation to each other. — Evan Thompson

I can sign up for that project. It makes sense to me.

It seems to be true. Though one could also argue that the ability to do that was conferred by evolution and it looks as if the planet is taking action to restore balance.

Yes, but I would draw back to the idea of the organism and natural selection working in lockstep. And that of the two, the one which was adapting was the organism. But in humanity’s case, we abandoned the adaptation, broke the lockstep and adapted to what we thought rather than what natural selection dictated.

That humanity has broken free from the constraints of natural selection and is endangering the whole endeavour. Going off on an ego trip and trashing the ecosystem which brought her into being. So perhaps the planet is now taking action. But is that the inorganic planet, or the organic planet (the ecosystem) or both?