.. Some considerations, I have collected, since the day
your question appeared :
Set language ..changing-default-language-from-command-line
Locales are in /use/share/X11/locale/ ?
I get this with the ' ls ' command :
ls /use/share/X11/ .. (there is nothing relevant in /usr/share/)
More than one problem if you want to change something :
There are no extra language packages for SliTaz.
The whole OS is a compressed file .. even after install.
It is uncompressed every time, you do a boot up.
But hopefully, all changes ( and package install's )
are saved when shutting down.