Re Japanese: no idea. Try to ask at https://forum.sailfishos.org/thanks. I gave it a shot and was able to install it on my SO-05K after editing the flash script (replace the H8314 with SO-05K basically and also edit the mdr list accordingly! aka put in the new mdr5 for the edited script).
everything seems to run fine, but sadly I couldn't figure out how to get waydroid onto the device... and then another issue popped up with is sadly somewhat of a deal breaker: I couldn't find a way to input Japanese text, which in Japan is kinda essential :/
I sadly don't have much time to experiment any further today, so I will covert it back to android (since this is kinda my daily driver).
I think I will try again after doing more research and in case Lineage continues to fail...
Re waydroid: It is packaged and distributed via Chum repos. See Waydroid instructions at https://github.com/sailfishos-open/waydroid, Chum install at https://github.com/sailfishos-chum/main
All in case if you wish to experiment later