Vtuber copyrights

I recommended that alias in that specific case because The Moon Studio is founded by Kaguya Luna herself (or at least in her name). I'm not so sure others have the same kind of security or if the companies they're under are that stable, and most vtubers are independent anyway. Using companies as copyright would also be difficult for most users to accurately track (the website you offered is in Japanese), and they don't really add that much to searches. People search for games and shows, not for companies like Upd8, which most fans of Kizuna Ai have probably never heard.

If policy needs to change, I'd just recommend dropping character tags, since as it stands using both is almost always redundant, and not having a copyright would make crossovers (which they often do) confusing. Copyright and character tags were designed around anime and games, where characters necessarily belong to something. Vtubers are more like individual people and don't necessarily belong to anything, so they can be described in one tag. The exception would be groups like Nijisanji, which in addition to having a clearly established brand name, has characters that frequently appear together and interact with each other. I think The Moon Studio is shaping up to be something similar.