I did acro classes a couple of times. When I was really young, I took an acro class at the local rec center because our local gym didn't have a pre-school class, and I was too you to enroll. We mostly did rolls, and some cartwheels. I ended up in gymnastics instead for a few years before taking up dancing again, where my freshman year of high school I took an acro class that was taught by one of the local universities cheer coaches, so us being older and her having the background for it we did work on skills up to front and back handsprings. After that class I switched back to gymnastics.
The thing that was the same both time, was I was taken back to the very basics again when I got back into the gym. So despite the fact that I had started to learn cartwheels at the acro class, I went back to learning proper technique for rolls and later moved on to cartwheels. When I went back to gym the second time, they even had me start back close to the beginning. We worked again on my cartwheel technique and my roundoff technique, and eventually I got to learning front and back handsprings.
My bad habits I have on my handsprings, I am almost positive I picked up in the acro class.
So, I guess I'm going to agree with the others and say to avoid the acro class, unless it is taught by someone with a gymnastics background. Since she is already in gymnastics, the acro class may easily bore her and she may get confused as to why she can work on certain skills in the gym but not at the dance school (or possibly vice versa.)