It's cool. I'm just stupid. -.- I have previously installed a translation for Rocket Slime 3, and for some reason I decided Not to actually look at the full TITLE ID when trying to figure this out, so I thought the folder for That game was a FFI Folder created when I installed FFI. Thankfully overwriting that didn't corrupt my saves for Rocket Slime, as I would have been doubly upset at that point.
It actually works brilliantly when you RTFM&FTDD. ;P
I'll take my shame and go now. -.-
Hey, now that I've discovered where I went wrong, I can point you in the right direction. You need to Create this folder (000400000005DA00) since it won't be there in the Titles folder (SD:/luma/titles/) unless you do. Then you copy those files into it. After that the game boots up in English just fine. ;P
You can watch this guy do it if you're still having issues:
ummm you mean to create folder with title id manually?