This is an official style question but relevant to classical only, so opening it here.
STYLE-570 suggests we should decide on a naming schema for the “op.” catalogues of composers. Right now they’re a messy combination of “ComposerName’s Opus” and “ComposerName’s Opera” - but the first is singular, and the second is confusing - since they could suggest it’s operas by this composer.
I’d suggest to use "“ComposerName’s Opuses” instead. Yes, yes, the term is originally Latin and had the Latin plural opera - that said, every dictionary I’ve checked except Merriam-Webster gives “opuses” as the first option for the plural, and even M-W says “opera, also opuses”. And it’s much less confusing IMO.