The administrator can add new languages to the language list. If a string is missing the English content for that string is shown.
To add a language:
Click Settings in the Menu bar and click Language in the side menu.
Click Add in the Language overview window. The Add dialog appears:
The Add new language dialog
Fill in the following parameters:
Language: The full name of the language (preferably localized, Nederlands, Deutsch, Svenska).
Iso: The language ISO-code (two characters, NL, DE, SV, etc.).
Click Save to close the dialog and add the new language to the Language overview.