How villager pools work is like this: When a villager moves away, but doesn't have any destination, they'll sit in some void/pool. Then, whenever you visit someone or they visit you, a villager in your pool might move into their town if they have a slot. So what I'm proposing is this:
Someone with an open slot will come visit your town and maybe time travel a bit, and see if they get anyone. If they don't, then they can just go back into your town or you to theirs, and then try again until Julian pops up. I'm not sure if it would work, since it'd be pretty random, but it might. And then, once they find Julian, they can TT them to the moving date and send him on his merry way to the original recipient.
Since I have a second town I'll be cycling through for villagers, I wouldn't mind helping. Especially since that seemed like such a huge trade! But it'll have to be in a few hours @_@