There is actually a small synergy between FV, Watchtower, and Island here because Island is kind of like a TfB card. I doubt that is very relevant; just feel like pointing it out.
More importantly, your strategy was inadequate. There is absolutely no need for Treasure Maps on this board with the FV-Watchtower combo, a massive surplus of +action, and a spammable +buy. The 4 $-producing terminals in this kingdom all fit into such a strategy and Steward can even be used as mid-turn trashing.
It's difficult to criticize the rest of your play when your deck development was set back by trying to collide TMs. One other consideration is that, especially with your opponent not trashing very quickly (since he did not open Steward), I think that you should prioritize trashing with Steward over getting and playing Mountebanks until you can get to the point where you may even be able to play multiple Mountebanks every turn.