The problem with the painted buildings is always the sky as it changes so much, there's no perfect way to do it.
The HTTYD show building concerned me when I first saw the model years ago but it's no where near as bad as it was, plus I think they've added more trees and theming to the building.
I'd be more concerned about the HTTYD coaster being able to see outside the land, especially with Stardust right next to it but that's the price you pay for a thrilling coaster.
As for sight lines in general.
Potter won't be an issue as you're surrounded by 4-story buildings.
SNW is equally walled in. Slightly interesting to note how the Mario showbuilding is coated vs the HTTYD building.
Monsters will be mostly fine with some outside seeping in when on the coaster but it's a spinner, so who cares.
Celestial park will have some views of the Orlando Eye.
We're getting into the final stages of construction where all the small guest facing things are being added in. Even if the outside world is going to be slightly visible, what's directly in front of you is going to be so overwhelming, it doesn't matter.