I'm 99% sure they all work as they're supposed to. To test it out you can check an item or customers stats in the shop screen, then do the upgrade and check the change in the in the shop screen or the customers sheet again. When it's not working right I will go and stand in a corner for an hour :) (hoping very hard you won't find the one mistake that might have slipped through somewhere ;)
We add many small things in here and there on every new series.