Install kde-l10n-zhtw by entering the following commands in the terminal:
sudo apt update sudo apt install kde-l10n-zhtw
Description:
zh_TW (zhtw) localization for KDE
This package contains the translation files for all KDE core applications for the language "zh_TW".
Homepage: http://l10n.kde.org/team-infos.php?teamcode=zh_TW
Version: 4:17.08.3-0ubuntu4
Section: universe/kde