The way the Japanese keyboard works, you have to press “Enter” in order to move onto a new character. In normal web browsing, clicking “Enter” in the Japanese keyboard doesn’t mean GO, or NEXT LINE, or anything like that. It just sort of confirms the character you’re typing and allows you to move on to the next, on the same line. (Example, if I used the Japanese typing mechanism to type the word “is”, I would type i → enter → s → enter)
In RemNote, this whole thing is a little buggy as whole sentences get deleted, or random spaces get added and stuff like that.
Totally get that this might have not been an ideal use case, but just throwing it out there (: