No, regionfour has no bearing over what language the game is, just that it can be played on an out-of-region 3DS.
If you want to play the Japanese version of Fates patched with fan translation, which is the closest option next to learning Japanese, you'll need to download either a prepatched version or patch the game yourself and play it via a CFW or flashcart. Or Citra, but I don't know if it's quite there, yet.
Alternatively, if you can get your hands on the Japanese version and the romfs for the fan translation, you can use Hans to play the hack without a need for any of those- though you will need a way to run the homebrew launcher.