For those using Gateway on any of the Variants of the 3DS, while the new Release has Cheat Codes, it does however have issues with .cia Files. In order to run any of your CIA Games or Homebrew, you need to run a .3ds/.3dz Game FIRST, then while in-game, hit the Home Button, dont close the Game, but instead select a CIA Game/Homebrew. Once you have a CIA loaded, everything works perfectly.........
Except for RetroArch. For some reason, you will need to either have a .3ds/3dz Game loaded, or (I think) you can have a CIA Game loaded and do the same as above. Hit Home, select and run a RA Core. Failure to do so will cause it to lock up after setting the Screen Resolution making you have to Force-Shutdown.
After you successfully run a RA Core, the rest will work as normal. Took me 2-3 test to make sure. Got the CIAs to load up, but the Cores got stuck for some reason. Then I decided to do a 2nd 3DS run and it worked perfectly afterwards.
Every time you turn on your 3DS Device and run GW, you will need to do this. Just so you know if you were not already aware. Hopefully they fix this at some point so it wont be a problem for everyone.