Random fix for Chinese on Linux/GNOME (Ubuntu 18.04) as an English locale user: I got annoyed by seeing the Japanese 门 character instead of the Simplified Chinese one. This was caused by the order in /etc/fonts/conf.d/64-language-selector-prefer.conf .

I copied it to ~/.config/fontconfig/conf.d/ , renamed it to 63- (not sure if that was necessary), and made the order the one that I want. So now my Noto CJK preference order is SC>TC>JP>KR rather than the default JP>KR>SC>TC.