Every account of the universe is grounded in brute facts, for which there is no justification. That hardly means we can't claim to understand things. I would say we understand consciousness more or less in the same way we understand nuclear physics: we have a very compelling ontologically flavored justificatory framework which both allows prediction and makes theoretical sense. We know quantum field theory is not the right theory of the universe. We may never know the fundamental theory. But it would be ridiculous to say "we know nothing about how the nucleus works."
Ah. I use the term "the subjective experience of consciousness". IE, what you are experiencing could really just be a VR drug hallucination, completely unrelated to anything else, or an epiphenomenon of a completely mechanistic universe.