Great tool, where to change the language in the Admin -> Localization does not exist.
GPSTRACE.pl / shellmix.pl
You change the language for the whole Vehicle Tracker application by going to Settings -> Settings -> Localization -> Language
Note that this is for the whole application and not only the Dashboard plugin.
Furthermore, you need to have the _ChangeLocalization privilege in order to change the Localization settings
Finally, the Dashboard plugin is currently only distributed in English,however you can use the Localization Editor
in order to translate it to any other language.