You might have to guess some parts if it is in JP. I upgraded from JP to AU and it worked fine (including GPS). I think I went from .59 (or something like that) to the latest (.7 something) in one upgrade.
I've done JP to AU on a 2014 Axela, everything works fine including GPS (which was a surprise as I was expecting it to break because I understood JP models have different GPS hardware). Radio bands still don't work, but I think that's a hardware issue (the frequencies are now the correct ones in software, but it still doesn't pick up local stations).