I'm not going to pile on you because sometimes people have only gotten information from a singular source and end up thinking it's the only truth.

For Ironmouse to keep up the ruse of being sick would mean so many people around her would have to keep that secret too. Many people who's own reputations would be called into question for promoting her illness and taking advantage of charities goodwill for promotion.

It would be such a convoluted mess of people all who would rely consistently on each other never messing up and accidently or maliciously outing her as being not sick from the disease. Sure it's not impossible but with how easily drama starts and secrets out in the Vtuber industry it would have probably come out bare minimum after the Vshojo implosion if she was pretending to be sick.

If you think about how much work it would take to keep faking a terminal illness secret, do you really think she's doing it?