You need to allow one tick of execution for newly created objects to actually be created and so that a loop/sub-event could pick and apply/get values to/from those instances (such as their X/Y).
In your case, I'd suggest, in event 174 to set global variables to the value of X/Y you are creating your object's instance at. You could then create your pre_effect instance using those global variable values.
Then, in event 175, instead of referring to the newly created pre_effect.x, you would refer to the global variable as well.