Thanks @Holunder9 and @faust, I agree with your suggestions for Rewording.
I don‘t think Visionary is too weak in terms of "too weak to be bought on a frequent basis". I believe that Visionary is strong on every board with a spammable card which lacks one of the engine components "draw, +actions, +buy". These aren't rare.
On the other hand, this mediocre strength wastes the best part of the card: playing with multiple visions, and managing interesting decisions when to call it and where to put the tokens. This will happen much more often if players get multiple Visionaries, and fight for the Vision split. It's a very interesting situation, if one player has a strong deck with 4 Visions (enabling two tokens per turn), and the other has a weaker deck, but 6 visions.
With this situation in mind, I agree with Holunder9 that it's better game design to buff Visionary, maybe even by a lot. I think I will test to reduce cost to 5$, with +2$ on top. I am pretty confident this won't lead to boring games, because Visions need interactions; also Visionaries become lousy terminal Silvers once the Visions are gone, which is an additional motivation to buy other cards.