You know what gets me about The Flash? Everyone talks about the season 3 Flashpoint. OMG they didn't do Flashpoint right! Duh, the whole damn show is Thawne's Flashpoint.
Flashpoint was never going to be that much like the comics version anyway.
Not only do they not have the budget, but they don't have rights to most of the characters.
But the one from Earth X is not from Earth 1 thus not from Barry's future by chance... if he's from another dimension entirely isnt it feasible that is who nora saw in prison in the future???
No, that was Earth-1 Thawne, he had just traveled to Earth-X. He said so himself.
As far as how he's alive after getting erased from existence twice just chalk it up to time travel fukkery.