Writing non-Latin languages
The default input method in Trisquel is "iBus".
If it's not installed on your computer, you can run:
$ apt search ibus
to see which input methods is supplied by(based on) "iBus". Then you can install then by:
(For example, followed command will install a chinese and a japanese input methods.)
# apt install ibus-pinyin ibus-mozc
Make sure "iBus" is selected, by click the "System Setting" in the "start/Trisquel button", then "Language Support". There will be a menu list for the selection. (As well, it can also be switched to others, see below for details.)
After that, you would press Ctrl+Space to turn on specific language input methods.
To adjust settings of "iBus", you can run:
$ ibus-setup
Other input methods
You can also use another input method such as "fcitx".
To view available input methods:
$ apt search fcitx
To install those input methods:
(Google Chinese input method, for example)
# apt install fcitx-googlepinyin
When fcitx is selected(see above), press Ctrl+Space and you will see the specific method that you install.