I run a similar deck. I have more control spells and run marionette master and bastion Inventor along with Herald. Bastion Inventor has saved me against targeted removal decks. Marionette master, while not an improvise card does have quick kill ability and works well with Tezzeret's -2 . I run yahenni's against aggro decks and have battle at the bridge to side board in against larger creature decks. I do pretty well at fnm though I struggle against fast aggro decks.

I would add some copies of Hope of Ghirapur cheap artifact early and serves as a Silence when you need to ensure Herald of Anguish or Tezzeret the Schemer stick to the board full turn, or make it into the board vs. control.

I really want to revisit this list/archetype with the rotation coming. We are losing practically nothing, so we defenitely don't get worse...

What are your thoughts of treasure?