In my experience, when flying CX F (I'm sure I've done this flying J too), I've always been allowed access into any of their HKG lounges the night before a morning flight. As I've said, even HKG security has always allowed entry, no questions asked. While I haven't done this post pandemic, I'd have zero hesitation to and would expect it would be the same now.

PS - I've even brought a guest in there with me a few times in the above scenario.