Just to explain to you what I see if happening, and why slash is asking you to move the action:
Each event has columns: The conditions and actions.
When every you reference an object in a condition it becomes “selected” for all matching objects. This selection is inherited by sub conditions as well.
Actions that reference objects are applied to all “selected” objects of that type. When you create a new object it becomes selected only for that current action (not sub events).
So in your case you are not referencing EnemyBasicAttack objects in any of your conditions, so when you preform an action on EnemyBasicAttack it assumes you want to apply that action to ALL EnemyBasicAttacks.
So you can either add a condition that references the newly created object (typically by setting and referring to a unique instance variable value) OR more simply move the action on EnemyBasicAttack to the action block where you created the object (and where it will be automatically “selected”).
I hope that helps explain better how it all works (at least from my experience as a user)