Matsuri is apparently very normal off stream, according to Marine.
Gura is dumb but not mentally ill. Her and mori are the most normal ENs. Ina is a would-be neet with probable avoidant issues, her only socialization used to be ff14 raids.
Watame is one of the most normal ones, people that dont watch hololive but still want to post exaggerate her lack of father figure because they have third hand information at best, to put her on the same level as Miko or Aqua is laughable.
Fubuki and Marine are monstruous otaku, Fubuki specifically is the female version of the simpson's comic book guy and jumped on the "pretend to be an anime girl online" train as soon as she could despite having the grades and money to do whatever the fuck she wanted. One of the few that went into vtubing because she *wanted to*, not as an singer/seiyuu/money move.
Nene has bimbo mentality on a normal girl body, much like Haato. They've been cruising on autopilot for 15 years. Not a mental problem, but 'dont care' is their default setting.
Okayu has been having image issues since highschool where she was called a fat nerd with a shit manly voice and she's been ignoring them for a decade. They're bound to resurface at some point because its clear she's not over highschool at all and she's just mentally avoiding whatever problems she has.
Mio is the oldest holo and she lives in the christmas cake society. She's bothered by this. Probably not bothered enough to stop acting like a 10 years younger wolf girl on stream, but she'll have an early mid-life crisis eventually.
Kanata is a massive recluse that avoids talking with anyone unless she absolutely has to. Part of the issue here is her mother being a complete cunt, making fun of her voice, goals, friends and achievements and calling her a lesbian for not having a boyfriend at 17. She probably is bisexual, though.
RBC is a colossal nerd with ridiculous, borderline autistic laser focus on whatever she's doing. Whatever she's doing she does it for 3-4 months at a time, not bothering with anything else until she burns out and does anything else. When she obsessed with her own character she redecorated her whole room and threw away her computer to buy a roboco one. And again she's a massive, massive nerd. Tied with Fubuki and Marine on overall geekiness.
None of these are narratives, they've either explicitly said or implied all of this. Its all true.
The rest (Miko and Pekora being avoidant reclussive autists, Noel being delusional about her two careers, Polka being depressed all day every day, Rushia being emotionally walled in, Aqua having actual autism worse than Pekora,...) are all pretty well known.