It was Manny. One of my favorite all time Seinfeld scenes was when Kramer comes out with his hair moussed and, in Spanish, Manny makes a derogatory comment about how much worse it looks and Kramer takes it as a compliment.
This is another very small Seinfeld inconsistency, because in the Busboy episode, the busboy goes on a rant in Spanish after his cat gets out and Kramer translates for George, making us think that he understands Spanish.
Here is an obscure one.....what is the name of the girl that Kramer had in Jerry's apartment when Jerry finally took back his keys from Kramer? He says her name after he leaves the apartment and then comes back in to get her.