Hello, i've installed KDE Plasma 5/Kubuntu for my grandmother in place of broken Windows 10. She doesn't understand English. However, there is no Bulgarian language listed in the regional settings. I tried reinstalling locales and locale packages, but still not showing up. Please help.

The availability of a language depends on the amount of strings translated for a desktop. Unfortunately the % of translation for bulgarian is not far enough to be included in a distribution as you can see here: https://l10n.kde.org/stats/gui/trunk-kf5/team/
The translation of a language is a volunteers based effort, so there are likely more volunteers needed for Bulgarian. You can always contact the Bulgarian translation team and help them getting more translated: https://l10n.kde.org/team-infos.php?teamcode=bg

Mamarok wrote:The availability of a language depends on the amount of strings translated for a desktop. Unfortunately the % of translation for bulgarian is not far enough to be included in a distribution as you can see here: https://l10n.kde.org/stats/gui/trunk-kf5/team/
The translation of a language is a volunteers based effort, so there are likely more volunteers needed for Bulgarian. You can always contact the Bulgarian translation team and help them getting more translated: https://l10n.kde.org/team-infos.php?teamcode=bg

That's so sad...

Can you point me to the steps how i can request to become a translator?

Subscribe to their mailing list: http://ludost.net/cgi-bin/mailman/listinfo/dict and check the website I gave you for instructions on how to translate. You will need Lokalize as a tool for the translation, but please coordinate with the Bulgarian Team as they might have assigned specific tasks.

I noticed this issue for Swedish language on latest Plasma in archlinux too. The Swedish translation is fare more completed than Bulgarian. Actually I was trying to test translation of some application in Bulgarian locally (for example Falkon). The application is complete translated with no issue inside main windows with exception for QDialogButtonBoxes of all windows (dialog boxes, message boxes, property windows) . The corresponding qtbase.qm is completed in Bulgarian. How are this QDialogButtonBox items in KDE translated? The Bulgarian language is not in the list of add language (Swedish too). I manually set the Format and Language in .config. The system Locale is set acoording archlinux's standard but Main menu items like Leave, System etc are not translated too. I looked in corresponding .mo file in /usr/share/locale/bg/ and those strings are translated. Why bypass the translator those files? How could I configure that to be translated?
With regards

You should get in touch with the Swedish team, then, this forum can do very little about this, and we have no influence on translation progress.