Hi there, @akoziol… you are in the best of hands with Adam, of course, and I could be missing something here, but I believe what Adam described is exactly what you need.
If you have a repeating group with a data source of
Search for Projects, and you add a text element in the repeating group with an expression that is something like
Current cell's Project's list of dates:last item, you should get the last date in the list for each project in your database. Have you tried that? If that’s not what you need, you might want to consider sharing some screenshots so it will be easier for someone to help.