This looks fun, but I'd be afraid that it gets a bit too ridiculous with the +Action token, Champion or Academy. Especially considering that these are very easy to insta-pile that way, which will leave one player with a massive advantage.
That's a really good point. I'll think about if there's a reasonably elegant fix.
Edit: it now duplicates itself at the end of your turn rather than immediately. This prevents you from emptying the pile in one turn. It still allows you to draw your deck pretty easily if you have a +1 Action token.
TL;DR, another below-the-line option might be to add "You may not put any player-specific tokens on this Supply pile."
It's not quite as elegant, but I think this might be a better option. Even in a Lost Arts-Smithy game, that strategy is insanely powerful, and frequently (in my experience) the only issue with it is that you so quickly have enough money to buy Gold/Provinces that, absent +Buys, you end up not getting that many Smithies (and sometimes have to go back to them when your deck fills up with green). A Smithy that gained itself would make the already powerful effect even more potent, even if it only replicated at the end of the turn (preventing piling).
But while the +1 Action token makes this broken, I don't know that Academy or Champion pose the nearly the same risk. If you use Academy to pile these, you only end up with 1 extra Villager, and otherwise it effectively makes them self-gaining double Lackeys (you get the effect of Lackeys twice, and both come with enough Villagers to be two Labs). With Champion, there's rarely any guarantee that you will get it played before the game ends, and Traveller lines do not get along well with terminal drawing. If you wait to start getting Missionaries until after you play Champion you probably will have little time to use them, and if you buy them early then you run the big risk of drawing your Traveller dead and having to wait another shuffle to use them.
I used this language in a draft of a card I ended up dropping. My first early designs for
WDC 102 was a card called Industrious Monks that was initially "+$2, return this to your hand," which I think I read was considered as a design for an official card, but was ultimately thrown out because if you got it in a game with no villages, it wasn't any fun to play with. To fix that, I added a Treasure-Map-like mechanic where if you trashed two IMs you could move the +1 Action token to a Supply pile (presumably letting you create a village as there is almost always at least one cantrip or disappearing money).
The immediate problem with that was that the obvious choice was to move the +1 Action token to Industrious Monks to make each give you unlimited money. My first thought was to have it put the token on a different Supply pile, but the interaction with Lost Arts still makes endless cash too easy. Next I added below-the-line text that said. "You may not put any player-specific tokens on this Supply pile." While this solved my +1 Action token problem, I soon realized there was also a Champion problem that I couldn't find a solution to, so I scrapped it.