She is very vertical like a golf swing instead of getting her torso to tilt.
This is why I asked if there was a view from the front on front toss. I think we would easily see that she is very vertical. If you can get her to tilt to the degree that the pitch height warrants, this will allow if not foster the better bat path that RDB describes. Something like this tilt toward the plate from the front---> ( _
^^Well, sort of, heh heh. I'm sure that if she is a slapper she has dealt with enough low-and-aways to be familiar with the tilt I am speaking of. Just ask her to add it to her swing away. There are some good things going on with her, so I would start with this minor adjustment and then see if the bat path still needs work.
One other thing that won't necessarily make her swing better, but will make her a better hitter is to completely reverse her vision path from beginning to end. Instead of setting up staring at the ball and then finishing with a head pull to CF, have her start with both eyes focused on an imaginary pitcher and then track to the ball-on-tee, finding the ball at/just before contact and then leaving her head/eyes there as she finishes the swing.
I'm the Dad of a switched hitter as well. Mine caught on to slapping quickly at 11yo, but has been a traditional swing away hitter for many years since.
Good luck and keep it up!