Regardless of how bad Cover is behind the scenes, this kinda proves that the "disagreement with management" statement and its variations weren't just mere "boilerplate statements" meant to deflect all criticisms towards Cover, the talents genuinely do have stuff that they disagree with the management.
Maybe it's just because I paid attention to her the most, but I feel like Mumei has given us the most details about what problems she had and made it clear that health was just one of the problems. Paraphrasing what she said; the cough sucks, but she could deal with that and keep working if it had been the only problem.
So then, a list. The 3d live she had to scrap and come up with something else (also causing her to lose her 1 million wish). This graduation live where Cover didn't make accommodations for her to have studio time. Her last trip to Japan they screwed up on booking her a place to stay so she was freaking out until everyone realized she could just go stay at Bae's place (Cover
did have a hotel booked for Bae though, despite her living in Japan). The Visa (though I don't think we know whether this was Cover's fault or Mumei's fault). Having no input in the choreography for It's Not A Phase (idol dancing to an edgy song, and Mumei probably knew that it was a farewell performance with Fauna, if not for herself also). All the PFP's she drew? Cover was supposed to put them all in a dropbox months ago because Mumei's not allowed to make her own file storage link, and they still haven't done it. And I feel like I'm still forgetting things that were mentioned in the past or even as recently as today.
Obviously many of these problems happened after deciding to graduate, but that is a LOT of screw-ups in a pretty short timeframe. Heck, I think everything I listed was all within the past 1 year, and that's only the ones she explicitly told us about and that I remember off the top of my head.
And also obviously; this does not contradict the fact that they all have different experiences and tolerance levels for different types of bullpoop. I just think it's FAR more likely that you're gonna get dicked around and screwed over if you don't live in Japan (and even more specifically, if you're not part of the JP branch).
Edit: and here's a fan project to get back into a somber mood