hai, i think we had a same problem in here. before i was creating a task based on blueprint_base class. it had on blackboard value change event. (that event fired when the value in the blackboard or result ) is changed (pretty much same with "“blackboard” decorator). and doin a checkin in that function (OnBlackboardChange), what i found is if we set the abort to self, it had fired ExecuteAbort event. so i think it would be a way from there.
sorry english is not my first or even second languange 