It is very unlikely that a user wants another default language and then changes the language in the menu. Even in that case he still is able to revert to his prefered language by editing the ppsspp.ini. It still remains as long as he doesn´t change language within the menu.

Also we are only able to retain it if ilanguage != 1, because it is already set in the config that way and because of that it wouldn´t change at all.

Or we split selecting the system-language and the ui-language of ppsspp into two parts, which would make it a little bit less comfortable.