If the back elbow starts down there is no moving it forward.
If the back elbow is low they do not start that cocked. You need to watch her and focus on the back elbow. Watch how the back elbow leads her hands. Just zero in it and you should see it. You've seen it on video and with a little practice you will see it, that part isn't to fast that with a little practice you will see it and correct it right away. Your like a mirror, identify the flaw and correct it. With any correction you start out slow, 40%, 50% and so on.. AND at the same time I would have her finish away from her body more.