Pay attention… via dpkg you can change layout for SSH terminal session and not inside KODI.
You can create you custom .xml file only for virtual keyboard and after that you can chose from setting:
The stock xml it’s in /usr/share/kodi/system/keyboardlayouts… you can create a .xml put inside… restart kodi and using only whit virtual keyboard.
If you have a hardware USB keyboard whit korean layout actually apparently it’s not possibly to change inside OSMC…
Other info can be found here:
or here: