Earlier quoted context omitted.
I would be extremely surprised if something as elegant, terse, and useful as the Fourier Transform had been missed by human mathematicians up until now. All expressible theorems are enumerable, after all (if we limit ourselves to a finite alphabet). It seems likely that any new theorems are long, highly complex and esoteric, regardless of human or machine origin.
1. The computer is going to struggle to recognize elegance. I’m not sure it’s relevant at this point (but who knows). 2. The statement about proofs is just way wrong. It doesn’t sound like you are familiar enough with them. This isn’t exactly what you implied, but witness the very short disproof of the Jacobean Conjecture.
That's a counterexample (finding a needle in a haystack), not an elegant proof. Proving the conjecture would be elegant, if it were true but somehow still resisted proof nearly as much as the conjecture did because the conjecture was false.