edit: i wrote this before the changes to the card, although I still worry about the too much money problem.
You want to errata to make the trashing mandatory? In four player, doesn't this earn you 8 dollars and a buy whenever you choose the trashing option?
If trashing is optional, I'm still worried it's too strong in multiplayer. Consider Alice, Bob, Charles, and Diana. Alice plays a Harlequin early in the game. From Bob's perspective, he can trash (minor benefit to him, minor benefit to Alice, no benefit to other two opponents) or not. Obviously he'll choose to trash. Charles and Diana compute the same. The result is that Alice gets an obscene amount of money. BC and D are in a prisoner's dilemma - it's probably worth giving Alice 2 dollars this turn to trash an estate and a copper, but it's not worth it if the other two players compute the same, but there's no way to enforce cooperation.
Maybe you just want to give $ for the trashed cards from the player's own hand?
It almost seems this should be two separate cards. I like the attack that gives junk actions, although it will obviously be much stronger on some boards than others (but that's fine). One can imagine a board where it's not very strong, but I think that's fine since it's never completely worthless (i.e. you can always flood the opponent's deck with more harlequins...).