One of the issues that I’ve seen is for “Orchestra plays soundtrack score music”. In that case, some people want to use classical style (it’s an orchestra doing orchestral things!), some people want to use soundtrack style (it’s soundtrack music!) and a lot of people have no idea what to do.
Honestly, my solution to this one would be to make soundtrack scores equivalent to classical music, have separate guidelines for pop-song soundtracks if needed, but probably just mostly deprecate the soundtrack guideline and say “if it’s classical-ish in context, follow the classical guidelines, if it’s a more standard popular music soundtrack, use the standard guidelines instead”.
The “opera - operetta - musical theatre” continuum is IMO more complicated. I’d treat all of it as classical releases, but that’s probably because I’m used to classical releases and I find the guidelines result in fairly clean, useful data.