fdc, I believe that method, GenerateCodes(), is actually for generating the Gameshark codes, so the RAM address, and not the WORLD.BIN file address, would be correct. Not sure why it's off by 4, though.
melonhead seems to refer to gameshark codes as "Codes" throughout the FFTPatcher source, and actually writing to the game files as "patches", so we'd need to look at the analogous method for "Patches", which seems to be GetPatches() (StoreInventory.cs:213), where we see:
PsxIso.StoreInventory is of type KnownPosition, which is made up of sector, start location, and length (the constructor for this type of object takes arguments in that order), and defined like this:
StoreInventories = new KnownPosition( Sectors.WORLD_WORLD_BIN, 0xAD844, 0x200 );
So it looks like it's already looking at 0xAD844 in WORLD.BIN for patching.