After doing some digging into Fortify SSC export capabilities today, I have found that in our environment, we do have a STIG 6.1 column being exported for the audit views for my project versions even though the DISA STIG report options in SSC and the Audit Workbench for 24.4.0 both contain only versions up to 5.3.  Once I figure out can figure out which API calls contain the STIG cross-reference data, I may not care about exporting the PDF reports through either native Fortify application anymore, but it does seem the data is present, just not easily accessible to somebody who isn't going to write a tool to flex the API.  Thanks!