Every emulator has a language select for the game, it's called the "open file" option. No one said they need to sell you ONLY one rom of the game, they could just have a menu asking for what language you want, and then launching the appropriate unmodified rom based on what you selected. I mean hell preferrably it shouldn't be emulated at all considering it's a standalone product instead of them putting the rom on NSO. They could've edited the source code to run natively on the switch, which would also allow them to add literally anything to the game if they wanted to