I just found another, bigger problem, with Music XML
That's much as I was alluding to with my "
BIAB often(?) gets confused by cut time, and probably also by other non-4/4 time signatures".
I couldn't at the time remember any specific examples and it was with 2023 anyway, which might(!) behave differently, but I think it does much as you show with many non-4/4 things.
It can be tricky to be sure where the problem really lies without going through the MusicXML manually, which is hard work. An XML beautifier would likely help. My patience has worn too thin.