Awww, I got here too late. The other coaches already found out the problem lol...
Some things that you could look for...
First:
Her lunge/hurdle might be cross-stepping.
Let's hypothetically say your DD is right footed. Her strong/lunge foot is her right one. In her hurdle, she takes her forward/strong foot and crosses her midline (imagine there is a line on the floor in front of her straight in front of her directly centered) in her hurdle. This can cause a slight twist, but usually is more guilty of sending kids off of a straight line tumbling path.
Second:
When your DD does her round off, check to make sure she is not tilting her head up to look at her hands. This can cause her back to arch, and absolutely nothing good can happen then. I'm guessing your DD's coach is a great coach, so its probably neither of these as they're both pretty obvious.
The last and most likely thing I can think of....
It might sound like a very small issue, but your DD could be planting her hands too wide in her roundoff.
This is important because if her hands are planting too wide, they will not leave the ground at the same time. If her right hand leaves the floor faster than her left hand, then the right side of her body is now traveling quicker than her left. This results in rotation.
Also if she is pulling down into the LO faster with one arm than the other.... = rotation (as another above poster stated)
It could also be none of these things. Just throwing some things out to maybe look for
