@Derpy I don't think the answer has to tell anything more about the first EG movie. Your answer is useful because it shows how her character is consistent to that depicted in the episodes of the show.
@b_jonas I may add some more examples that often get unnoticed
Take the "Pony Pokey" song. It fits everything the other mane six are doing at the moment, and Pinkie would have no way to know that other than "rule of funny"
Anyway, I have also rechecked the comics. No indication of any possible "human Sunset" anywhere, so that other question will stay unanswered.
@Derpy Why are we looking for the human Sunset? Isn't it possible that the Sunset we know in RR is originally from the human world, which is why she's so familiar with the humans, but stumbled to Equestria early somehow? Then there'd be another Sunset originally from Equestria, who may or may not be the same as Sunburst from S5 E26.
@b_jonas Even if the movie didn't make it clear that she came from Equestria and was originally a pony, the EG 2013 annual special had the pre-EG1 plot covered, so that is somehow sorted out.
@b_jonas would seem pretty strange that Celestia would use her as Twilight Student Template beta 0.5b
also, the not so good 2014 annual has her state that her "family" is on Equestria.
(which opens more plot holes than it closes, but all the 2014 annual is filled with those - at least from a credibility viewpoint)
(it is supposed to take place during Christmas after EG2, yet all the mane 5 are very ready to dis-trust Sunset again for something she didn't had any reason to do)
