Adding the H to some of these letters wouldn't give the right sound for native english speakers. I would transcribe these vowels using american english like so:
It looks like there might be a slight misunderstanding, "e" is pronounced as the e in "metal", "test", "wrench".
We do not use a different sound for it, and it does not rhyme with hey at all :D
Adding the H to some of these letters wouldn't give the right sound for native english speakers
I think the only one that could be tricky would be the "uh" since it could be confused with the interjection "uhhh", but as you mentioned, it is indeed pronounced as "oo".
First time I hear about that! Haven't talked with my Colombian friends in a while, but regions are indeed getting stronger differences every day although it is mostly with the marked s, c, g, h, j, r sounds, rarely with the vowels.
Anecdotally, I've never met a spanish speaker from any country (Colombia included) that pronounces the "e" as "ey" though, so it's interesting to think how that can happen. For context, tv and people in general use that pronunciation to mock (in a satirical way) English speakers trying to speak Spanish.