I don't think any of them, EN, ID, or JP, are mentally ill. At least, not outside of the normal scope of things. Clearly, some suffer from burnout, and most, if not all have had to deal with depression at some point. Some just deal with it better than others. But everyone has their limits. I think the stress of having to constantly watch what you say and having to satisfy thousands, hundreds of thousands, or even millions of fans can absolutely drive anyone a little bonkers, and I think the majority of the talents handle it pretty well... I'm not bragging when I say this, but I've been known for my voice my entire life, and I can't game with an open mic because as soon as I say something people start "Ohhhhing" and "Ahhhhing" me and asking me questions or if I'm a vtuber, what mic do I use, blah blah blah, and just waiting in a game lobby listening to that every match is enough to drive me crazy, so I don't know how the Holomems can be on air for hours on end multiple days a week with millions fixated on them and their every move. So ultimately, can you blame them for being a little loopy?
I also think a lot of them were severely bullied growing up, or even into adulthood. Even so, none of them really seem to have a mean bone in their bodies, I think most of them are pretty sincere and genuinely care about those around them. Especially the JP girls. I have no doubt each one of them has each other's back
The EN girls are pretty cool, since I actually know the language it's easier for me to pick out who's being fake or sincere. Like, I mean they're all kind of fake "support me, give me money, I need money" blah blah blah, they're all kiss asses like that. But on the basis of being a good human, I think they all do well in that department.
The only one I truly can't stand, like, at all, is Cali. If there's someone who's disingenuous and fake, it's her. I literally can't stand it every time she opens her mouth to say anything. I'm sure we all know what a greasy "Sheba Warrior Princess" she is. Fuckin' gargantuan woman, not fat, just a huge bitch. Fuckin' greasy hair, terrible makeup, actin' all tom boy'ish, and then goes into Cali mode begging for money and talking as just the sweetest little buttercup to butter ya'll up. It's nasty, she's fake, and I dislike her with a passion.