Referencing Order Initiators in Output Sets

We use the Custom tab of a constituent record to input order info for our Education programs. We create a standard order to track payments, but perf dates/contact info/geographic data is stored in the Custom tab and that row is then linked to the order. Once linked some columns are populated by order-level info (initiator, basic constituent data).

We've figured out how to create output sets which would allow us to pull data from the table the Custom tab references. The fact that some columns pull directly from the order is tripping us up.

I've tried creating an output set element that pulls the initiator column from the Custom tab table, but we get blanks. Simply pulling a list and specifying ticketing role doesn't seem to be working either.

Essentially we'd like to know how to reference the order info and the table where this would be stored. There may be some simple SQL solution!