From the questions you've sent me and from what I can tell in this thread, you may want to have a discussion with her coach so someone can show you the adjustments she needs to be making. Much of this is difficult to describe without referring to some basics that should be mastered before she even begins working the back extension roll. She should already be familiar with the following terms plus many more:
3. Open shoulders
4. Prone or push up shape
There are many more that should have been introduced by the beginning of level 5 but those are needed for this particular skill.
The ability to do a straight arm backward roll to Prone, or to a Pike or Straddle stand is a progression to being able to do a straight armed back extension roll. If she can't do the straight arm roll, she needs to work them in the gym on a down hill first then turn that into the extension roll.