Your question. I don't think Chalmers is saying 'it can't be done'. I think he is saying that it is a unique problem which differentiates it from all other phenomena that science seeks to explain. The reason why it is a unique problem is because we only know of the qualitative nature of experience because we experience it subjectively. Science is good at explaining objective measurable phenomena. It has not found a way of bridging the divide between objectivity and subjectivity... but note the paper referenced in my previous post

‘Qualitative assimilation, phenomenal experience and Being’ (QAPEB) is a paper that was published in Biosemiotics journal at the end of 2018 (it can be accessed and downloaded free). Its publication was the culmination of 32 years work. It addresses ideas relate to subjectivity, objectivity, and the hard problem.

The first thing to say about it is that it claims to bridge the objective–subjective divide. The objective–subjective divide is the problem of how to explain why an objective world has subjectivity at all: why is it that an objective world has 'given rise' to agents that possess a subjective view of the objective world?

The second thing the paper does, is provide a viable answer to the hard problem of explaining the phenomenal qualitative nature of conscious experience.

QAPEB solves these two problems by explaining how and why three distinct ontological categories have emerged and evolved. Each of these categories is tackled in separate sections and inform the title of the paper.

Section 1 explains how it is that a world of physical properties became a world of qualitative properties.
Section 2 is concerned with how it is that the world became differentiated in individual creatures in a qualitative, spatial and temporal way, and in doing so, characterises subjective conscious experience.
Section 3 explains the emergence of the realisation of self-reference and of the self-identification of ‘being-in-the-world’.

Each of these ontologically distinct levels can be thought of as characterising the objective physical world in a particular kind of meaningful way (hence being published in a journal of biosemiotics), where 'meaningful' refers to such things as qualities, space, time and belief. One of the key claims in the paper is that meaning is generated when there is some kind justification of value. Certain physical mechanisms satisfy this requirement and facilitate the generation of meaning during their interactive engagement with the environment.
What we find in each level is a different kind of physical activity that creates a different category of meaning about the world. This is why we get differentiated ontological categories and an explanation of subjectivity in objective terms.