I was going to post some encouragement to this thread ten days ago, but...........
So now all I can do is say great job on the recent progress, and to keep in mind it's just that....progress and not the conclusion of the bhs saga. It takes time for some kids to mature on any given skill, so tell her to be patient, do lots of reps with spot as long as the coach is willing, and in time the skill will become a non issue.
Low and medium height beams are a good place to build confidence, and IMO kids (or coaches) tend to feel pressure to take skills to the high beam thinking that's the only true measure of competence. Certainly, they have to get comfortable with them on the high beam, but I'd argue that a regimine of five on the floor beam followed by two or three on the medium beam (repeated 3-4 times) contributes more to the goal of a high beam bhs than one white knuckled bhs with-out spot on the high beam after lots of hand wiping, finger wiggling, and shoulder rocking to prepare for that one attempt.