To localize MobiDB user interface please follow the steps given below (works in Windows 10 only):
1) Go to Control Panel > Clock, Language and Region > Language
2) Select the language you would like to be used as MobiDB interface language and move it to the top of the list by clicking on 'Move up' button
3) Run the MobiDB app to see whether the UI was localized correctly. In case the UI language was not changed, then most probably the selected language is not yet available for localization.