To play devil's advocate, I do understand the spot once and walk away in terms of helping the mental state, mainly because no one is touching her, they are just standing there....and if it really mentally is what your child thinks will work, it probably WOULD work, and she would be able to gain her confidence back and move on. My dd, newly nine, had a similar situation like that with a different charming trick on beam. The damn bwo, which is nowhere near as scary, however trust me when I say her heinous fall was. And yes, each practice for about a week, once she got it back to high beam, one of the coaches would stand there....first for a few reps, then one....after a week, she was back on target. Coaches never stood there again. She didn't need them to anymore.
Sometimes, there are kids out there that just need that bit of reassurance mentally to make it on their own. Some call it a crutch. I do not...particularly if they are younger children. Yes, I get that this sport ages our kids before their time, but 10 years old is not very old. Now if they stood there every darn day for weeks on end, hell yes I would think it was a crutch, and a problem too! For my child, it lasted 5 practices, and was done....I know all this because my child likes to use me a therapist in the car on our long ride home, so she spews out the practice details while eating dinner, and I drive the car and try and make irrelevant comments like that's nice dear, or that sounds cool/interesting (I am waiting for the day when she shares nothing, I know once puberty hits it is possible...right now she babbles away). I credit the coaches with knowing my child well enough to know what she needed. And it gave mine the confidence to go for it on her own. I should add that each day the one "watching" stood a bit further away...until on the 5th day the "spotter" wasn't actually spotting at all, lol...
The fact that she has been stuck in the situation for a long time means something probably does need to change. Is there any chance of a private, where she could gain more confidence? Have the levels been decided for her team? Any chance of talking with the coaches, or are they unapproachable? I do get that every coach out there has their own philosophy. It sounds like your child is doing great, and I am sure she wants this badly, so it is really messing with her emotionally.
I am sorry for her angst, and your situation. Sending good thoughts...