Level 6 is a hard level, but it's not uncommon for a gymnast, or even whole gyms, to just compete one meet to score out and move along. It sounds like your DD has mastered the level 5 skills which is a good thing in terms of progressing with minimal glitches, but fear is also a big factor as kids get to the upper levels with quite a few of the skills in level 6 being pretty big stumbling blocks for lots of kids. However, if she has been uptraining and has already mastered the level 6 skills and has a good grasp on the level 7 ones, and is likely to get the remainder of them by meet season, I don't personally see a problem with skipping ahead. But I'm sure her personal coach has a better idea of how quickly she picks up skills and how prepared she is, both mentally and physically, for levels 6 and 7. A conversation certainly wouldn't hurt, and like others have said, if your DD initiates it the coach might see her dedication and be willing to think about a plan.
But 10 years old is definitely not "too old" for the compulsory levels, so I wouldn't worry about that too much.
Good luck!