In this case having the property set to "true" would mean an event would be sent to event subscribers.
One thing to note though is since the definition of this property, we've created a Task Message Registry. I would recommend using events defined in that registry for sending task related events. Unfortunately the property name uses older semantics for eventing we've since deprecated, so that might be a bit confusing.
However, regardless of the state of the property, you can always log task state change if that's something your implementation requires.