Do you mean the relationship credit, or the artist credit? I think it makes perfect sense to list the names in the vocal credit (soprano vocals [Character]: soprano), but wouldn’t want to see it as the artist credit (soprano vocals: Character).
It is, to some degree, but it would probably be pretty decent if it was more standardized. I’d love to get support for something like “Roles” for an opera or whatnot. I guess that’s kind of just instrumentation, but still. Something like “we expect a recording of this work to have a soprano (Character 1), a tenor (Character 2) and an orchestra/conductor”.
i have thought about a separate branch of the database devoted solely to such an end, mainly to serve opera, musical theatre, and i dunno maybe other genres I’ve not thought about.
the structure would be quite straighforward: eg, an opera/musical main work would have its principal roles listed, and what vocal registers (mainly opera/operetta, sometimes musicals even) those roles were written for, and who were the cast members & year for every known production of that opera/musical. this becomes then an internal reference source for recordings, to be used in whatever way that may be useful/implementable.
Audio dramas would heavily benefit from a proper method too:
Another problem is the lack localisation in vocal attribute credits:
If I were to enter character names in e.g. Japanese people who can’t read Japanese are going to be unhappy and if I were to enter transliterated names those who do know Japanese will be upset.