I'm not sure if you originally posted that she only went 8 hours a week. To me that makes a huge difference, especially if her coaches are not working on flexibility. I know what I said before about being on team but I was under the assumption that she went more hours than that. My daughter at that level was already putting in 16-20 hours a week. They worked on flexibility and her coach stretched all of them at the end of every practice.
If she's only going 8 hours and they are not working on stretching her then this coach comes in and tries to stretch her like a seasoned gymnast who's crazy flexible that's wrong, especially when that coach is saying its the ONLY way to do it. So my mistake for mis-understanding your situation.
If I were you I would have your daughter stretch at home, every day!!!! I stretch with my daughter for 1 hour outside of gym everyday. I know it sounds crazy but when I go into her room in the morning to check on her I sometimes find her sleeping in her right or left splits. I don't know why she does that, I asked her and she told me its comfortable for her. We call her our little "freak of nature" because we think it's strange and funny. Ask a coach you trust or one of the coaches on here for a stretching routine and just stick with it everyday. I guarantee if you do that outside of gym her flexibility will get better and better.
Good luck and stand by your daughter. Do what feels right