@chinx2 she doesn’t need a performing arts teacher recommendation. But it can help, if the recommendation will allude to depth of experience, talent, working with others, etc. etc. As I wrote, it can also be part of an arts supplement if talent and experience warrant one: with video, resume and LOR’s.
@Twoin18 the process for the BFA is different from that for the BA (as others have said). BA applications generally have no audition so a supplement or extra LOR may be appropriate.
I would ask the schools individually if they accept a LOR from outside of school.
It would be helpful for anyone involved to use the term “health” rather than “mental health.” It is up to your daughter what she herself reveals, but teachers and GC should just use the term “health.”
The fact that your daughter continued/continues to do good work academically is important. There is no need for excuses at all. Her academic performance alone proves she is able to overcome challenges, in the context of the GC mentioning the health challenges.