okay sooooo idk if I'm getting this right or not
this timeline is the third reincarnation. First timeline is elira being evil n shit. Elria reincarnates which sends them back in time somehow and she meets reid. They both die and reincarnate AGAIN into the future. The other guy with guns was in the first timeline I'm guessing.
first branch extends, they reincarnate back into the first branch and then it splits off because elria doesnt become a demon queen ig
From what I understood, it's basically that with a caveat: Elira turning back the clock created a new world, since that very act is magic and the point in time she targeted didn't have that. So the world retconned itself into having magic from the start, leading to the evil empire's destruction in a butterfly effect.
As for the initial world's continuation and the alien hero, I guess the empire decided that it didn't have enough to invade in the original world and is eyeing the current one.
On another note, I'm on the fence with this twist. I know some stories have done the whole "time travel" stick and managed not to completely fail, so I'll wait and see.