You've made it very clear that you don't speak Japanese, and so all you're going to end up doing is one of the following:
Pointlessly translating it to English over an insane period of time, which by the time it releases wouldn't be worth it as everyone would have by then finished it on PS4,PC and Switch.
Copying the text from the English PC/PS4 release and inserting it into the 3DS game. Which results in a script not being owned by you, unless you edit so much of it that its no longer recognisable.
Neither option is quick, and only one of the two ends up in you 'owning' the script.
Also, you can't really 'own' something thats a translation of another language, because its still the original companies plot and dialogue, just given different words, but the same meanings.