I think that SharePoint 2010 didn't have any loop actions - if I recall correctly, you had to sort of roll your own, so that may make this difficult. What is the criteria you count on in List 1? I'd guess, roughly, that if something in List 2 changes, the count in List 1 would change for multiple items. And you'd need to get all the items that should change in List 1, loop through them, and update them. Here's a tutorial on looping in SharePoint 2010 - I've not followed it, so can't vouch to its accuracy, but hopefully it can get you pointed in the right direction: https://www.rbaconsulting.com/blog/tutorial-how-to-loop-through-multiple-list-items-without-code-using-a-sharepoint-2010-workflow/
Hilary Stoupa
