You should realise that you are using a software system - free of charge - that exists thanks to the dedication of hundreds, thousands of enthousiasts. Not only from the work done by people who form the Lubuntu-team.
Architects, designers, software developers, packagers, testers, technical writers and translators, to name few groups of people, are involved in a continuous process of making each and every component better.
An operating system is like a layered cake. There are many layers of software involved, and hence many different groups of people or organisations do their thing. Hopefully what they like best and are good at. Depending on the area (the kernel, a specific OS, a specific application) some, or even perhaps many of those people get paid, others certainly don’t.
Software evolves. Every major or minor update of any software part in the whole chain may require new translations, or adaptations to existing translations.
A lot of work involved. It seems that in your case, the translations you miss have not been provided in the respective language-pack (in the case of the respective *.desktop files you’ve mentioned the translation provided by the “X-Ubuntu-Gettext-Domain”-mechanism).
You can read more about that here: UbuntuDevelopment/Internationalisation/InternationalizationPrimer/Gettext - Ubuntu Wiki
I’ve been testing it in the Spanish language on Lubuntu 22.10 with the Castillian language packs installed. Same situation here on 22.10: the translations do not show. They just may not been provided (which is unlikely since there will be many Spanish language users of Ubuntu/Lubuntu around the globe), or something else is wrong.
Since the layered-cake-ish-nes of software and responsibilities, it is maybe not the primary task of the Lubuntu team (which I am not a member of) to assure that all and every bit of needed translation is provided. “We do our best”.
First we need to find out where the error lies. Seems you’ve have done your research already, and maybe know how to use a terminal. If you’re interested, try the following:
# check if your required language-packs are indeed installed:
$ apt search language-pack | grep "\-es"
WARNING: apt does not have a stable CLI interface. Use with caution in scripts.
language-pack-es/kinetic,kinetic,now 1:22.10+20221013 all [installed]
language-pack-es-base/kinetic,kinetic,now 1:22.10+20221013 all [installed,automatic]
language-pack-gnome-es/kinetic,kinetic,now 1:22.10+20221013 all [installed
language-pack-gnome-es-base/kinetic,kinetic,now 1:22.10+20221013 all [installed,automatic]
language-pack-kde-es/kinetic,kinetic,now 1:19.10.0ubuntu1 all [installed]apt search language-packs | grep "\-es"
# get a translation (available, and shown on your desktop)
$ LANGUAGE=es_ES gettext -d software-properties "Additional Drivers"
# get a translation (also available, BUT NOT shown on your desktop)
$ LANGUAGE=es_ES gettext -d system-config-printer "Printer"
The gettext application queries the various language packs for the desired translation. You can skip the “LANGUAGE=es_ES” part, since your desktop is already using Castillian. I am using American English on my desktop, and need this “trick”. This trick works only, after installing the given language packs, which I did, of course.
The -d-part is not
hocus-pocus, but tells the gettext-application which ‘domain’ to use. It is the value of the ‘X-Ubuntu-Gettext-Domain’ qualifier, as specified in the related *.desktop file.
As far as I know the correct, and correct number of “language-packs” have been installed (at least on my system).
My conclusion is that the translation (in this particular case) is properly provided, but not used by the part of LXQt that should handle it.
To be continued.