The LLM is making stuff up. Changing the trigger type isn’t going to do anything for you in this context.
For now, you either need to use one of the other langauges, wait for the PR to get merged before addressing this requirement, or using ooooone of these much more complicated approaches described in Design Pattern: Manual Trigger Detection. the Proxy Item appraoch is the most full proof.
Why won’t using postUpdate help you here? Because it surves a completely different purpose. postUpdate will only update the state of the Item. But anything can update an Item so using postUpate doesn’t give you any additional information. And an update doesn’t cause the device to do anything. It only changes the Item’s state. You cannot turn on a light using postUpdate.
On the other side, sendCommand usually results in a follow on update. For example, if a command to turn on a light is sent, if the light isn’t already ON, following the command there will be an update and then a change event.
You can’t use any of this to determine where the event came from.