The coupon does say "Carnival World Buffet" so that likely means they would not accept at the Seafood since that isn't the same place.
Just a side note we did visit the Carnival World Buffet on our visit a little over a week ago. It was good, however they have shrunk down since our last visit 6 months ago. They closed the whole station to the far right side and walled it off (permanently according to the staff). They moved some things around so things weren't in the same spots they normally are located.
