The language in which the user interface of Apama Analytics Builder is shown depends on your user settings in Cumulocity IoT. See the User guide at https://www.cumulocity.com/guides/ for more information.
Apama Analytics Builder currently supports English and German, even though Cumulocity IoT supports further languages. If Cumulocity IoT or the browser is set to a language that is currently not supported by Apama Analytics Builder, the user interface is shown with the default language, which is English.