I would be wary of using their calendar app. It has had a long-standing bug in basic timezone / DST handling:
https://github.com/SimpleMobileTools/Simple-Calendar/issues/... https://github.com/SimpleMobileTools/Simple-Calendar/issues/...
https://github.com/SimpleMobileTools/Simple-Calendar/issues/... https://github.com/SimpleMobileTools/Simple-Calendar/issues/...