These high up locations don't center the fireworks over the castle. In fact, they appear "layered" (one behind the other) because you're partially looking at the side of the show.
The low out of the park locations, such as the Poly beach and Narcoossee's deck lose some of the view of the lower fireworks due to the tree line.
Wishes was designed to be seen from Main Street USA and in front of the castle. That's where to go to see the best view. I recall being nudged forward by the crowd one evening so that I ended up on the street close to the bridge going to Liberty Square. The fireworks, at times, looked like they were above me. It was, in a word, awesome.