Doesn't sound like a kid that would be a favorite of a coach then anyway, and I'm not sure I understand what the beam situation is. A bwo on any kind of high beam is harder than it is on the floor and coaches won't out a kid on a wide high beam without making sure they can do it on a foam beam first because a fall is always more dangerous from a height. I would hope the coach is monitoring this, perhaps she caught the girl and told her to stop, who knows.
Quite frankly, I think other parents are bothered that this kid comes twice a week and cheats or whatever it may be and sounds way more advanced than the rest of the group (if this kid is voluntarily attempting walkovers on any high beam and other kids are doing kickover down a wedge, then she is way, way, way more advanced). But it doesn't surprise me because every kid develops at a different rate and this is often most apparent in developmental groups (for example, when I start a preteam, at the end of the year, some girls will remain in preteam while some will go to level 4, some to level 3, so you essentially have three levels). Everyone has the same opportunity, but some kids progress much faster, or are older. I will take kids up to about age 9 and as young as 5. So obviously there's a lot going on. Parents often have mistaken assumptions that their child "isn't getting to" work on something. But I simply use a system of progressions that isn't capped so if a child is able to do something, they work on something harder. This means some kids will learn the entire menu of level 4 skills in preteam, while others will not even master the pre-level 3 requirements to move on. You have the perfect storm of huge variability and parents who really don't understand how it works.
I once had a parent make the same exact complaint, other girls were "getting to" do roundoff back handsprings, and when was her daughter going to get to try? Meanwhile her daughter literally couldn't do a standing back handspring without being carried. I didn't have any reason to prevent her daughter from doing it, but she just had no back hand springing skills yet, while the other girls had their standing handsprings already. It's really not about "trying" but parents always assume their child could do something if they just got to "try", it is very difficult for them to understand it really doesn't work that way.