Locale en_IL should not exist - it's he_IL or en_US, en_GB etc.
I've installed Manjaro with just English, and that was fine. When I added Hebrew on the Language menu (KDE settings > Regional settings > Language) some system text, like Pidgin's menus, then defaulted to Hebrew, even though English was set as my main language and that had never changed. I eventually found out that the environment variable LANG + /etc/locale.gen + /etc/locale.conf defined my locale/lang as en_IL, which does not exist AFAIK. Hebrew should be he_IL. Changing en_IL into en_US fixed everything. Pidgin must've fell back to the secondary language, and when I didn't have one fell back to en_US.
So what I'm suggesting is:
- Change en_IL into he_IL. I'm not sure where that is set in the source code, couldn't find it.
- Show an error on the Languages menu if a locale is not found and fallbacks are used.
I'm not 100% sure this is the place to post this issue, but I found similar tickets here.