It's easy to use the Japanese head unit if you have half a clue. Google Translate on a smart phone can do real-time transaltion of the display on the phone screen....makes sense of most of it. Beyond that there are YouTube videos and printed manuals with translations.
Yeah that is why I asked the question. It doesn't make much sense seeing as the japanese headunit is still quite usable. It is a bit of an annoyance but it seems rather drastic to loose all the other functionality.