I'm using a 60 to 70 pin converter on my Retron 3 to play Famicom games in my room. Since it's cheaper (and easier) to get an NES Game Genies, would I be able to plug Famicom games into the converter and use Famicom Game Genie codes for the Japanese games that aren't available in English, like Transformers: Mystery Of Comvoy? Also, if I had a Famicom version of a game like Legend Of Zelda or Dr. Mario, would I use the NES codes, or the Famicom ones? I have a Twin Famicom in the living room (the Retron is for playing in stereo and when someone needs the big TV), so I'm starting to buy more Famicom carts, but some of them would be kind of cool to use a Game Genie on, and the codes are conveniently available online!
As far as hardware is concerned, yes, it does work. As far as whether NES codes will work on Famicom games, it varies from game to game. At a high level, it depends on how a FC game was changed before release on an NES. We have a thread here for listing FC Game Genie codes: http://www.famicomworld.com/forum/index.php?topic=1402.0 (http://www.famicomworld.com/forum/index.php?topic=1402.0)