What I understood ... **Zero faces** are faces too small to keep such detail in print and would be degenerated (simplified) by printer in final result. 

In reality ... Each printer is capable of some minimal step in print (resolution). If you will have an ornament detailed by small faces lower than degenerate value is set, than addon informs you those faces wouldn't participate in final print in such details and could be simplified by limit of printer step. Or it is just saying - too small to be noticed and topology can be simpler for given step.

If you scale model in edit mode, merge by distance or lower degeneration value in addon they're gone.

In your case nothing will happen if you ignore it.