Before I went to WDW in October, I saw posts commenting on the metal ramps used to get on & off monorail cars; they were not universally thought to be easy. I used a
scooter for the first time for this trip (previously used a push wc, so not an issue).
I really did not find the ramps to be a problem. I sometimes backed up to hit the ramp just right and sometimes needed to try a second time, but I don't profess to be the world's best driver! It's like any ramp, you want to back on straight and have enough speed to make it over the edge. They are like the metal ramps to get on & off the boats. I imagine your dd's wc is narrower than a sccoter so it would be even easier for her.
When I got onto the monorail, bc I had read about people having trouble backing up, I stopped once I was inside and didn't pull all the way thru or otherwise move around so it was easy to just back out straight again (not an issue on the boats as I was always able to turn around). Worst case scenario: if for some reason your dd had trouble, you would be with her and could scoot the ramp as necessary to line up (I was by myself). I found I needed a bit more speed going forward onto the ramps than backwards but I think that's bc I had a three-wheeled scooter.
Pixe dust to you, your dd, and your family! I can get flustered, and this was not something that fazed me at all.

Cupcake