It might actually be the case that the dress NPC doesn't exist in the US version. The sprite is definitely there, but the NPC might not be assigned to the roster of Baron NPCs. If that's the case then the dance event might still have all the instructions for the dress, but then the dress wouldn't do anything because it's not there.
This is all speculation. I'm reading/writing this from my bed, and my chrome remote desktop app can't seem to connect to my computer at the moment to test the theory. If you get around to it before me, try this: open the game in FF4kster, open the NPC editor, see if there is a dress NPC in Baron. Also, open the baron dancer event in the event editor, see if there are movement instructions for the dress (if there is, in fact, no dress NPC, then the instructions will be for "-Unknown-").