sorry in advanced if this was already said/posted.
alright just so you know where I am coming from, I have personally won 4 national championships for jump only, 3 american cheer power nationals and 1 COA nationals.. granted i'm from ohio so not huge amounts of kids compete in the category and i'm not by any means calling me some expertise proffesional jumper but here is my advice..
I am 4'10 and a chubby cheerleader, I am not very flexible. have right leg split, almost left and ehh soso on middle. Toetouches are all in the hips and power.
... you have to rotate your hips back like pushing your but almost like you're trying to get it in front of you and work to point your knees all the way behind you like (to the back wall) and when you jump make sure you are pushing off the floor. (if that makes sense) when her jumps do get big she will drop her chest a smige to compensate so she doesnt end up jumping and landing on her back..
my 3 best jumps are 1. pike. 2 around the world. 3 toe touch.
now, i'm more flexible in my right leg split but i jump better with left hurdlers/herkies and my toetouch is always uneven because my left leg is hire..i believe .
it's a lot of practicing, stretching and working your hip rotations. I WOULD NOT reccomend jumping with weights they are awful on your legs and ankles. some people say you should..i'm telling you not too. I know you keep getting told to practice and that's what you have to do, but make sure you are practicing correct technique or it's not going to benefit you at all to practice wrong. I would also practice hip rotations .. Ex: get a mat and sit on the end or of stairs and circle your hips/legs up out and around and dont let them touch the ground in sets up 5 or 10 ..
with hurdlers it may be the way she's thinking about the jump i always tell girls when i give jump privates to try and kick yourself by your ear and kick your back leg to your back... i make the younger ones pull their scorpions and tell them that's where i want their back leg so they under stand the "split" concept of their legs. sometimes it's just that younger ones dont understand they have to split their knees when they do the jumps.
with pike jumps, just make sure she thinks up not down and forward when she jumps so that her whole body comes up and folds not down and reaching for her feet !
hope this helps !