Well, as far as creator credit is concerned, Enix played no part in FFX. HOWEVER, when Squaresoft merged with them to become Square-Enix, SE bought all the rights to everything Squaresoft. That means SE owns FFX now, and therefore can put its logo on it, even though SE didn't exist when the game was originally released. It's kind of like the FleetCenter in Boston. When it was originally built, it was called the Shaumont Center, but Shaumont Bank got bought out by Fleet, and they changed the name of the stadium. It didn't matter that the building already existed, and technically, Fleet didn't build it. Things like that happen all the time. It's business. Whoever forks over the cash gets the right to display their name. That simple.