@George-Hatzisymeon, sorry I never responded to this. I just noticed it because someone upvoted it.
I just verified that the offCommand commands.json value is supported in the current version of the Raspberry Pi agent. If you were using that version and it didn't work, then maybe you were missing this part:
"allowParams":"true"Here's an example entry I just tested. It turns my led strip off if the parameter was off, and if the parameter was on, it turns the strip on and makes the leds green.
{ "trigger":"Green", "command":"\/root\/killrun.sh leds.py green", "offCommand": "\/root\/killrun.sh leds.py off", "ground":"background", "voice":"green", "allowParams":"true" },