Trigger severity names and colours for severity related GUI elements can be configured in Administration → General → Trigger displaying options. Colours are shared among all GUI themes.
Default trigger severity names are available for translation in all locales. If a severity name is changed, custom name is used in all locales and additional manual translation is needed.
Custom severity name translation procedure:
msgid "Important" msgstr "<translation string>"and save file.
Here msgid should match the new custom severity name and msgstr should be the translation for it in the specific language.
This procedure should be performed after each severity name change.