From everything we've seen, it seemed the Romulans never really had the stomach for an out-and-out war with the Federation.
The Romulans didn't shy away from war with the Dominion, granted with the evidence in hand, it was in the interest of their self-preservation.
Self-interest is what motivates them and generally wars cost more than they're worth. If they did find out about Sisko's gambit, it could lead to war. Of course it could lead to them making territorial demands like say cede us the Neutral Zone or something. Even if Sisko's evidence was fabricated, the gist of it was likely very accurate.