The japanese console should work just fine with UXE. The memory layout might be a bit different than a console running the english language. Therefore, you might need to add in a few s.xtf (scrap fonts) alongside the UXE fonts to get it to work. Since you don't have any games worthy of a gamesave exploit, hotswapping is your only option unless you feel like placing the chip into this box for the time being so you can transfer the necessary files to the xbox. Then remove it when youro finished. (Probably not very likely if you have a solder setup).
Hotswapping is really an art rather than a skill in my eyes. It takes time and practice to learn to do it correctly. If you don't get it right on the first shot, keep trying. You will get it eventually. As for causing any damages, I've heard these rumors but I have yet to damage my PC or xbox.