Thanks for posting here! Lemme give you my thoughts. I generally tend to focus on what's unique/interesting/never-been-done, because I've been around the Variants forum for a while, and other people usually handle the Balance.
Phionex: As others have said, this is too powerful. That being said, the concept of a trasher that replaces itself like Engineer is interesting. It's mainly the trashing that skews the card, especially with the drawing. I would make it
+1 Action
Trash up to 2 cards from your hand. If you didn't trash any cards this way, trash this and gain an Action card costing up to , and play it.
A bit Vanilla, but whatever.
Robber Baron: Insanely weak, and not interesting. The cost is expensive, and the
is tacked on, and Gold gaining is boring. I don't think you can save this one.
Money Changers: The wording is bad, and the concept is iffy. I'm guessing you and your group like the basics of the card and if you do that's fine, it should just maybe get some better wording, probably based of Masq:
Each other player reveals their hand. You may pass a Treasure from your hand to any other player, to gain a Treasure from their hand costing up to more.
Crop Rotation: I would just have this skip your action phase next turn. It's not anything new under the sun, and maybe a bit too powerful.
Occupied Village: Done before, and it has a problem of either boring on it's own or too powerful in tandem with other cards.
Land Grab: Counting points on a Victory card has always been a problem, and you can tackle however you want. With a vanilla bonus it sounds fun though.
Master of the Mint: I like it. It should be worded:
Play a Treasure from your hand, then trash it. For each coin it produced, take 2 and 2 Coin tokens.