Sorry, I don't know what you mean by 'mind is existence'. For me 'mind' and 'existence' are two words that have meanings in other contexts but not when equated.

'Mind is existence' means only 'mind is [a part of] existence', therefore these words are not equated, but rather related as a part and the whole. If the whole of something is existence than its part is existence two.

To view language as 'representalist' or 'nonrepresentalist' is not enough. I think that in addition to that we must regard it as a spectrum of 'substantivist' or 'nonsubstantivist'. Mind is existence, but it exists as some kind of mental substance. So as far as language is 'nonrepresentalist' it is 'substantivist', in the sense that it is some kind of 'matter' our consciousness is made of. We create/make our language from our mind-matter, and this ability is innate in humans, even if words in it are not related to anything and do not represent anything. Therefore I agree that language is much more than a representation of something. However, there must be a global structure of consciousness which encompasses both an object and a word and coordinates them, otherwise words would not have a denotative function. However, it certainly is not an exhaustive characteristic.

The concept of 'existence' may mean different things, but I mainly see two of them - existence inside the mind and existence outside of the mind. What is 'inside' is an illusion, meaning that it is not reality itself, only its representation; what is 'outside' is the absolute emanating all things, including our minds. The mind is self conscious and knows it is (existence), an external object is just an idea derived from induction, but never 100 % certain (being as logos). We may never prove for sure that we are not imprisoned in a matrix of our selves. Every person has this uncertainty and carry this suspicion till the end of life. There will never be enough proof that I am not the only person, hallucinating the reality which does not exist outside of me. In this case, I would be my own creator, the absolute, otherwise - the absolute should be an objective reality. Weather existence is relative or not depends on what it is related to, if it is related to something external, it is 'relative'; if it is related to itself, it is its own foundation, that is the absolute, which makes it 'absolute'.