Fcitx doesn't work

I'm a language nerd. I need to be able to type lots of different languages, because sometimes discussion of words come up in conversation.

The default input method (ibus?) doesn't work at all. I add input methods in Region & Language > Input Sources, and I press Super+Space to switch them as indicated, and the keyboard still writes Latin characters instead of Cyrillic.

Fcitx has more input methods and works for me when I type Japanese with fcitx-mozc, but no other languages (like Russian, Hebrew or Greek) will work. The input method will be switched, but the keyboard will not type different characters.

Things I want to be able to type:
- Japanese
- Chinese
- Korean
- Arabic
- Hebrew
- Cyrillic

This worked on Slackware.