Is there a way to let homey know when a KAKU device is turned on by a switch and not by Homey?
Maybe with MQTT in between or something. Or add the KAKU switch to Homey as well.
I know that KAKU device doesn’t communicate back, but maybe someone has found a smart solution for this instead of buying all zigbee dimmers.
No, there isn’t.
Only the Zigbee kaku devices can be checkedfor their status.
The 433MHz models only receive commandsand cannot report their status.
You could indeed connect the switch to Homey, but then the switch only reports to Homey that it tried to switch on a light. If it was succesfull is not reported.
Not sure if you can add de KAKU switch to Homey, but that is how I solved it with my ELRO RF sockets. I added the remote/switch to homey (the ELRO app supports that) and set it to another channel. So now when I press the remote/switch Homey picks up the signal, en then turns on the socket for me.
The below worked for the “old” KAKU app (before version 7). I am not sure if it still does for the new one because I disbanded KAKU when the new app came out:
If the code transmitted by the switch is the same one that you used to learn the light in Homey then the states will match, because Homey then uses the same code for both. This will work for only one switch per lamp.
With a lux metering 
But then I would buy a Zigbee dimmer
