You can provide the app menu in various languages. A sample ZIP file can be found in the following article: Individual App menu (app_menu.xml) . 
This area of the app is not controlled by the language app (more information in " Translation of Texts in Your App ").

The language of the visible menu is selected on the device. Purple DS app recognizes the general language settings. Country codes like "en" (= English) and "de" (= German / German) are derived from ISO 3166 ( ). If the device is set to a language that is not explicitly listed, the app will default to the default settings.