"empty" box
 

Does anybody now what function is of the "empty" boxes in for example the ButtStomp Scenery event?

They just don't work, simple.

Well, your level shows us quite the opposite, Cooba...

Well, it works exactly the same without the parameters, Jazzmusic.

The empty box has a use, it can be used when creating an MCE, but the method is kinda outdated.

PurpleJazz is basically right. Buttstomp Scenery has parameters because all the block events do, and it seems logical to assume their codes were copied from one another. The first one might have been intended to be a Wait parameter... it's impossible to say. Regardless, their only use as far as we know is for use in MCE's, where they provide the exact same functions as any other parameters on any other event would.

Could you then please explain why you gave the field a value?

Because I was a n00b and didn't know how it worked, so I just copied it from Violet. Later on, me and him learned that the values were useless.

Actually, after looking at that level, the buttstomp scenery parameters are doing something, it's just not noticeable. :P *needs to rewrite that article...*

Well, I removed the parameter and tested the level, showing that cooba was right.
But if they are doing something, is there a way possible to find out?

Honestly, in that level it doesn't matter. The only way it would matter is if you took a warp from far away directly to those blocks and stomped the question-mark block instantly, in which case not all the blocks would disappear. As it is, no matter what the parameter is, it all works perfectly.