I wanted to support new CornerComplication and get this error when submitting:
Invalid CLKSupportedComplicationFamilies. The value for CLKSupportedComplicationFamilies in the Info.plist of 'Time Guard.app/Watch/Time Guard WatchKit App.app/PlugIns/Time Guard WatchKit App Extension.appex' contains an unsupported value: 'CLKComplicationFamilyGraphicCorner'.