I have always been a locale-fallback feature user. With Lubuntu 18.04 LTS I haven’t any problem:
I can’t put a link here due the st*pid limits.
The computer users are fluent in those languages, except in English (the default one). If there’s a string untraslated in one language, it jumps and try to show the string of the next listed language and so on.
In most of the programs the fallback works, but the LXQt menu, some details like some dialogs, don’t work well, even editing /etc/default/locale file:
LANG="pt_BR.UTF-8" LANGUAGE="pt_BR:pt_PT:gl_ES:es_ES:en" LC_NUMERIC="pt_PT.UTF-8" LC_TIME="pt_PT.UTF-8" LC_MONETARY="pt_PT.UTF-8" LC_PAPER="pt_PT.UTF-8" LC_NAME="pt_PT.UTF-8" LC_ADDRESS="pt_PT.UTF-8" LC_TELEPHONE="pt_PT.UTF-8" LC_MEASUREMENT="pt_PT.UTF-8" LC_IDENTIFICATION="pt_PT.UTF-8"
It doesn’t work even installing and configuring locales with language-selector-gnome, which is not installed by default on Lubuntu 20.04.
If I try to change the main language, I see that most of translations exist, either in one language or another. So the problem is with the fallback, determined by the LANGUAGE = section in /etc/default/locale.
We are not the only ones with this problem, polyglot people or inhabitants of regions with languages with two different spelling regulations can be combined in this way.
Perhaps the LXQt desktop environment has the language configuration files in another location. It needs to be reviewed.
Thank you for your attention.