How to add Custom Sublist data to a Freemarker Email Template

I created a saved search to be used as a sublist on the customer record, so that I could then add the results from that sublist search for each customer to an email. It looks like below, but the transaction header fields from the saved search sublist are not showing up in my email.

Before I did this, I tried customer.transaction.otherrefnum, as an example and nothing showed up then either. I would prefer simple, if someone has had success with this, but don't mind this custom sublist route either, if it can be made to work?

My goal is that all overdue invoiced numbers, dates, etc, are listed out in the table for each email to each customer. The top of my email contains the summary, like total amount outstanding, etc. Below should be this table with the detail in it.