The effect will only change how your sprite is displayed, it won't change its collision box.
One way to implement your idea is to add a second animation (using the same sprite), and changing the collision box of the second animation to match what you need.
The event will look something like this:
On collision -> Set Sprite animation to [second animation]
But then, That would leave less creativity in what I am doing. It is supposed to be that it randomly chooses a number and set it as how "pixelated" that object is. Unless you expect me to add a couple of hundred different animations for each possibility, there should be an easier way?