The Mobile MapWorks 2015 app does not include translation files for the German language locales for Austria or Switzerland (i.e. 'Deutsch (Osterreich)' or 'Deutsch (Schweiz)' a.k.a. 'German (Austria)' or 'German (Switzerland)') on Android devices so when the tablet is set to one of these languages the user interface defaults to English instead of German.
The workaround for this problem is to set the language for the Android tablet to ' Deutsch' or 'Deutsch (Deutschland)' a.k.a. German (Germany) which will allow the user interface to be displayed in standard German.