MQTT fixed it.
Thanks rjblake!!

Now, when I switch a light, or change the dim level, I see the result almost instantly on my iPhone.

For others having the same 'problem'.
Only three steps are needed:
- Install Mosquitto, there are plenty tutorials.
- Add the MQTT hardware in domoticz, see Domoticz ...

Domoticz: v3.8153
Homebridge: 0.4.33
homebridge-edomoticz: 2.0.11
Z-wave Fibaro modules
Zwave.me USB stick
RaspberryPi

The problem is that Siri doesn't know the state changes not done by Siri itself.
I like to run around in my house and tell Siri to switch lights on and off. But when I leave home ...