That is not supported in any shape or form with Apple's SDK, especially as MobileSheets is running as an iOS app, not as a MacOS app. It's just not possible to programmatically force an app to be in the foreground. I suppose you could send a message to Gig Performer asking if they can support forcing their app into the background, or to minimize after triggering the event you want triggered, but I'm not sure if that is something they would want to support.
Mike
Mike