I've been playing the game as if every time a Treachery card is revealed during setup, you complete its effects. Is this correct? Thanks in advance!
Treachery Cards revealed during Setup
Yes. That is the correct way to play it.
FAQ point 1.19, page 5
(1.19) Card Effects during Setup
“When Revealed” effects are resolved if the cards are revealed during setup. A player can trigger responses during setup, following the normal game rules. Players cannot take Actions during setup.
That's what I figured. Thanks!