Translation sources of GUI strings

The translation of a GUI string can have 4 different sources:

Qt

As Frameworks, Plasma Workspace and all Applications are build upon the Qt™ libraries, you need the Qt™ translations for your language to have a fully localized GUI. Therefore go to Qt Localization and check if your language is already translated.

Frameworks

Frameworks are addon libraries to Qt™ which provide a wide variety of commonly needed functionality. These libraries with their translations are used in Plasma Workspace and all Applications.

You find the translations in l10n-kf5/$LANGUAGE/messages/frameworks

Plasma Workspace

You find the translations in l10n-kf5/$LANGUAGE/messages/kde-workspace

Warning

The list of Available Languages in the System Settings module Translations has only the localized language names of System Settings translations installed and available on the system.

Therefore it should be your top priority to translate the file l10n-kf5/$LANGUAGE/messages/kde-workspace/systemsettings.po.

Without a translated systemsettings.po users will not be able to select your language using the GUI

Applications and application libraries

Any other folders in l10n-kf5/$LANGUAGE/messages/