What do you mean by,
one running task can quickly overlap to the next depending on the key selector?
I’m guessing you are talking about task interruption? If so, then yes, if you set observe aborts to “self”, it will interrupt the currently running task and execute the task with the satisfied decorator condition.
If your pawn sensing is setting the decorator blackboard values, then yes, it will trigger the interrupt. Say, if the AI “do not see the player” task is running currently, and soon the pawn sensing (in the AI controller class) triggers the sight, and you can set the blackboard value via the AI controller to change the respective blackboard value (in this case a simple boolean tick should be enough). This will trigger the interrupt inside your running task and execute whichever the task that the blackboard value satisfied.