To describe this world is not to describe reality 'in itself', as it is independently of how we regard and describe it.
What impressed me about Plato and Sartre was their conviction that we should live our lives in the light of big truths about reality and human existence.
It is indeed impossible to describe reality 'in itself', but that does not mean that our lives are answerable to nothing but our own conventions and commitments. They are answerable to a way of things that transcends the reach of our conceptual schemes.
I think that Asian versions of 'ineffabilism' have an advantage over the best-known Western ones, like Schopenhauer's. They are free from the dualistic image of the world of experience as the joint product of mind and reality.
There are really three players: 'absolutists', for whom it is possible to describe reality as it anyway is; 'constructivists' or 'humanists', for whom there is nothing beyond a world that is relative to human interests and conceptual schemes; and 'ineffabilists', like myself, for whom any describable world indeed exists 'only in relation to man', as Heidegger put it, but for whom, as well, there is an ineffable realm 'beyond the human'.