@Uggla, I can't download because I'm not registered there, but is it correct to simply put the missing synaptic.mo file into the directory /usr/share/locale/sv/LC_MESSAGES and then restarting Synaptic shows it in Swedish? I believe that should be it, right? If so, then this could be the solution to get other applications showing in the new locale. Yet, I will not go through 73 languages and browse the net for potential missing mo-files for all kind of applications

@ scoundrel: as said, the amount of translations strongly depends on the chosen locale, some of them are virtually 100% (German (KDE homeland), French, Spanish,...), some of them medium, and some only marginal. Addlocale only applies what is there already. You can get a rough idea on the degree of translatability here:
http://l10n.kde.org/stats/gui/stable/team/@samuelbh: thanks for the reply. For addlocale I have the following hopes, it should
- provide an easy solution to switch the desktop & system locale (obvious)
- help spreading PCLOS into the non-English community
- easily make available what has been there all the time because addlocale only applies already existing translations
- honor, and hopefully stimulate further, the fantastic work of all the translators
- serve as a starter for a localized remaster by always downloading the very latest localized programs and without the need to provide all kind of additional files on the CD/DVD, which after some time would be outdated anyway.
- finally, get your feedback in order to improve the script and make it better for the good of all the above

@melody: Just install addlocale via Synaptic and run it, it can only get better...

OO and much more will be in French. If you are in Europe please use the European mirror servers, the Irish, Dutch, and Swiss servers are very fast.