About the WoD
I am also a little confused about what exactly happens with them. If they were able to use the echo like the Ascians they could just grab a corpse and live on, just like the sahagin that put his soul into the body of the other sahagin. Maybe Alphinaud did not know it better and assumed this and we will later learn that this is not true? I am also not sure why exactly they want to go back to their own world if they just die there anyway. It makes much more sense if they somehow end up being alive since they would be able to met their friends again. But if they stay death than they could have just stayed here. (And made sure that the WoL wont mess up like they did)
And its told that their world is only on the brink of ending like the 13th so it was probably saved by Minfilia.
About Mide and Alex
Maybe someone can say if I am wrong but does the ending of Alex mean that somehow Mide and her boyfriend are the founders of their tribe but at the same time somehow lived at our time too? Were they reborn and are still kinda in an endless circle? I mean they are born in our time, "die" there and are sent back and founded their tribe only to be born again later to start the event with Alexander? @_@ So in a way since they will always end in the past, does this mean that they will never be reborn into a better future? Or maybe its just something SE overlooked? This would also make the two the first true cases of reborn people. We only ever heard that someone will be reborn if they die from the scions but never saw it first hand....ugh my brain hurts