I'm quite convinced.
There is a paper trail a mile wide, starting with these two docs, with notes by W (left) and C (right) on the bank statement, and McConney, W's no. 2. McConney's notation that the amount had to be doubled "for taxes", and his testimony that this was what W told him to do, wraps it up.
It is not reasonable to conclude that TFG did not know he was reimbursing Cohen, who paid off Stormy on his behalf. To argue that he thought he was paying a retainer to C, you would have to believe either 1) Neither W or C (or M) told him about it, to protect him--and banked on him paying nearly half a mil to Cohen without question in monthly payment for 11 months, or 2) He was too busy to pay attention to the checks he was signing--in which case you still have to believe no one told him (and that he threw over his lifelong system of bill paying).
All they have to prove is that he was part of the conspiracy; they don't have to prove he directed the details of the payments. The mafia don is still complicit when he tells his hit man to "take care of it" even though he doesn't participate in the murder or direct the choice of weapon.
I remember in the Phil Spector trial, when the despicable Vincent DiMaio appeared as an expert witness for the defense, and argued that Lana Clarkson had shot herself in the mouth, a suicide, whilst sitting in a chair next to Spector's door, with her purse of her shoulder. Also not reasonable. BTW, the defense trashed Lana up and down the public highway--though unlike Cohen, she didn't have a history of being a lying shit, and was dead.
The first jury hung 10 to 2. But hat doesn't make the story any less absurd and unreasonable. Happily, the second jury nailed the POS.