The deal wasn't explicated as being with the Tal'Shiar, no.
It's quite probable that this intelligence organization was indeed the party that would have received the Fed-gathered intel, and the party that originally promoted the deal. But it's also possible that the Romulans have a separate military intelligence organization that would be the recipient, and Tal'Shiar is just the secret police that doesn't do anything so mundane. They probably concentrate on torture, coercion and monitoring of their own, as well as of external enemies of the state, plus the occasional harebrained military-political scheme. A bit like Gestapo vs. Abwehr in the Nazi Germany.
However, the bumbling of the Tal'Shiar would be certain to hurt the reputation of the regular Romulan military intelligence, too, and might well negate the original treaty. And as said, "Visionary" may have been the breaking point already. That's the last time that we really hear of the agreement, at any rate.
Timo Saloniemi