I think the fact that this is a non-terminal makes it ridiculously powerful. In many decks, chances are quite good that it reveals at least two actions and gains two coin tokens. You cannot really compare a coin token to a Copper or two tokens to silver, respectively, because you can accumulate them. So gaining those two tokens is already quite good. If you have a Village and/or multiple Theaters in your hand, you could gain 4-8 coin tokens if you get lucky with your opponent's hand. If not, it's still a Lab or a Peddler every time you play it but strictly better than both of them for the possible additional benefits. I think it would be priced at $6 accordingly.
Let's consider this without the +action. Then it's at least a Moat and at best 5 coin tokens. It gains you 2 coin tokens on average without card draw which would be really weak for its unreliability. $4 for such a card would probably be overpriced. So the +actions make all the difference here. The problem with your original concept is that it's swingy (which is okay for the possible powerful effect) but when it reveals two or more action cards, the effect is stackable (because the opponent's hand remains the same) which is insane.
My suggestion would be, if you want to keep it a terminal, to make it look at the top two cards of the deck of the player to your left and discard them afterwards, like tribute. This way, you can play multiple Theaters consecutively and might still get very lucky but the card retains its swinginess with each use. This would be priced at $5 accordingly.