"He who marches out of step hears another drum." ~ Ken Kesey
What dpi are you using for your seperations?
If you're image is applicable, maybe try index instead of sim process. Has worked great for us many times. (More forgiving).
For spot color WOW, are there colors that hold up to getting stomped better than others? Or is it best to stick to smallest part of the design to largest regardless of color? If the former is true, could one of the WOW pros in the house list some standard colors by their WOW printability? Are there specific colors that should always be printed last (or first) if possible?