wow...my DS12 the same way.
A 70yo trapped in a 12yo body. Little old man.
I would say your DD12 would be fine waiting...but I'd Fastpass as to minimize the wait. Also... use a Walkie Talkie or Cell Phone. Tell her to shop around the exit shops or sit on a nearby bench.
I've talked my DS12 into trying Space Mountain this year.
He road Test Track 2 years ago and loved it. So I told him that Space Mountain wasn't nearly as fast (55mph vs 28mph). Ride was a little Rougher but all in all SM is pretty tame for a Coaster. A little cash incentive to get him over the hump and he agreed to ride.
Same Technique worked for Splash Mountain.
Told him...he need to turn his

into a

!!! 1st he had to realize that he's 99.9999% safe and get over being scared and enjoy it for thrill factor...cause nuttin's gonna happen.
I told him I used to be terrified of Coasters...until one year I was with a Church Youth Group at Opryland USA (RIP :

). I rode some Coaster-like Ride that was in a half pipe (Screamin Demon or something). It wasn't that bad so I rode another True Coaster (Rock'n Roller)...WOW...I was hooked!!!

Took me a few years to work up to one the went upside down though.
Anywho... if she's dead set on NOT riding then I think she'll be fine...just use Fast Passes and have a way to communicate. Good luck!