I don’t have this relay, so I can’t tell for certain, but I don’t see how it is showing status updates when the physical switch is toggled. My friend has this switch and I was looking at his logs today. It is very similar to the Philio PAN04 in that when the physical switch is flipped, the relay sends a SwitchBinaryReport event. This event does not specify which physical switch is flipped. My device type for the Philio, when it receives a SwitchBinaryReport, requests for the switch to send it an updated status using the COMMAND_CLASS_MULTI_CHANNEL_V3 command class.
The original SmartApp for the Enerwave would fix this problem by requesting a refresh every minute or so to update the status of both switches. That is why @CDJ is seeing all those null object errors in his logs. The SmartApp is requesting a refresh from your device type about every minute, and then the system is throwing that error.
I had my friend try my Philio device type with his Monoprice dual relay and it works well. Status updates and all. Looking at the log, it looks like the devices act the same except the Philio supports energy reporting.
If anyone wants to try my Philio device type out, below is the link. Also, one advantage of my device type is the SmartApp no longer needs to trigger a refresh of the switch every minute. I’ve included a link for that as well.