Like most have stated, it would depend on the squad/school. I was a cheerleader from the time I was 10 years old till I was well into college. I coached for many years, and even did judging at tryouts and competitions. I can tell you, when I tried out for all my squads, tumbling was never done by me. It just wasn't a requirement. In my senior year though, the school did pay for us to have a tumbling coach and we all learned to do in competition. But still, only a few actually did them during the routine. I never expected any one of the girls who I coached to tumble, but if they did, I worked that into the routine. And I wasn't overly harsh when judging girls who didn't tumble either. It just depended on what the squad/school was looking for.
Your DD friends would be told at the first tryout meeting what the requirements are. They will be told what routines they need to do, what grade point they need to have, if they need to sign anything up front, and if they need to tumble. All that would be told to them at the first meeting. If they can't meet those requirements, then they shouldn't try out. Tumbling will benefit them, but they may be able to make it on the ability to just do the routine. But they should be told by the advisor ahead of time.