To be honest, since the end game here is to save Jinny which would then enable Euca to save himself, it might just be that. I think that wishes are the key point here, I always did feel ominous reading parts where the wishes would call Euca "wish-granter". I mean, why would they call Euca wish-granter when wishes themselves are supposed to help people achieve their wish. So, I'm kinda leaning on Euca becoming some kind of god of wish to make everything that went wrong, goes right, maybe through the combined power of the wishes. Though, I don't really want this kind of ending, it feels sad cause it might transform Euca into a wish and be erased from the lives of the other characters. But I really do think memories spilling over would be a thing, Halley pretty much given us a clue when we transfer over to Sissel route B.