No comment on the teaching or anything else, but a couple of asides. If she missed the exam because she chose to attend a brownie trip, the school may have a policy that you need to pass the exam to move up. All girls have to make choices along the way. There is nothing wrong with choosing a brownie trip over a ballet exam, but it is a choice.
Secondly, it is not unusual at all for the older dancers who intend to dance professionally to take classes at an additional school. This is nothing to with the quality of the original dance school, as the OP is concerned 'we just found out'... but merely to do with getting in enough dance classes at the right level. One school will not run their Advanced foundation classes every night, for example, so very often the girls will take the same classes at an additional school as well, to get their hours up. It's very common here. The dance schools usually have an agreement such that the dancer can only only perform for the original school.
12 is about average for pointe round here. I think dd1 was 13, but I could be wrong. She's definitely not going to dance professionally, it's just for fun (ten hours a week of expensive fun. Sigh.)
I would be chatting to the dance school, if I am honest, and making sure that when the next exam dates are posted, that dd understands if she wants to do well, she needs to practice, and attend any additional prep classes, etc etc. and actually take the exam. They can't not move her up with a pass in hand - you can ask the school if there are any extra classes she can take to improve and get through the next couple of grades faster, or so that she can join the grade 1 class if she improves enough.
It's unusual that she has decided this may be a career for her at 9 if she has never taken a formal exam though - is it maybe still a little girl 'oh I want to be a ballerina' pipe dream, rather than a 'hey, I am pretty good at this, and I love it'. Usually the gals with dreams of professional dance careers are in class every night and sitting every exam that pops up, and acing them... but maybe she is doing that in tap and modern, and it is just ballet that she is struggling with? Where is she with the tap and modern classes?
If it helps at all, our current dance school didn't start exams until three years ago (now RAD) so there were a lot of girls who didn't take any exams until much later. We still have girls picked up by professional dance companies. At 9 she has plenty of time. Most kids pass the first few grades though - it's not rocket science. Dd2 passed her g2 last year and she has cerebral palsy...! Maybe the school want to wait until they ace everything?