I'm not sure why you'd need to know international business days. Top rated seller shipping is based on how quickly you ship item (from here in Canada) so only our business days would apply (I think!?)
If you mean a package arrived one day late because of an international holiday where you were shipping too that seems extreme given there is always a range for estimated delivery. Are you sure this is reason?
Seller Dashboard should show the place/reason for losing status. Does it show as late delivery? or late shipment? Maybe there is another reason. More often it's from the number of items shipped (ie. you have to ship at least 100 items to US in year) than one day late. Can you give more details?
