I believe this is still accurate, but probably not too critical for most users.
Afaik that the actions following a created object, for that object, are exclusive to the newly created object in that event regardless of currently picked objects. The list of currently picked objects carries over to subsequent sub events as normal, but does not include the newly created object.
The key is that newly created objects, outside of the immediate event they are created in, cannot be picked normally until the next top level event.
Using the on created trigger, and the system pick last created condition will give you finer control.
The normal way to pick and manipulate multiple instances of the same object involves using families. If you put the object into a family then you will be able to pick and reference between the sprite object and the family object.