I sometimes write in German and French, which means non ASCII characters.
I don´t know if I just need to edit keyboard preferences to a different kind of keyboard (like US international) or if I must install whole language packages. I wouldn´t mind having the dictionaries and autocorrect for libreoffice, but after selecting the languages it also downloaded help guides in these languages and several regional variants of English (za, gi, ca…), which I don´t need.
The system is in Unicode throughout, so it can handle any language, whatever it’s set to. The only thing to check is input. Maybe use a compose key, and or switch to international qwerty.