- Edited
We have some common ground but I'm afraid you slipped up on the "E# major scale"
SouthPark E♯, F, G, A♯, B♯, C, D -- and then finally back to E#
We don't usually have a scale written out as "E# major scale", which doesn't make it impossible. Did you try playing what you wrote out at the piano, before posting? (I always double check) Try it - it doesn't sound like a major scale. A quick indication is that E#, F .... are the same piano keys, and B#, C are also the same piano keys.
I've written out an E# major scale, and juxtaposed F major. If you play these on the piano you should hear the same thing.
E# to C is dim6 (what you were after)
F to C is P5
That's a quick check, because you'll be playing the same piano keys. We know that dim6 = P5, and we also see and hear it.
However, in the E# major scale there is no C. There is a B# ---- and E# to B# is a P5. It also fits neatly.
This was kinda fun.
The problem happened in trying to write out this interesting scale. It happens. That's why I try to play what I write out before sending, to make double sure.