If I understand the issue I think this should be an easy fix.

I personally prefer spooling to individual files and not overly familiar with spooling into sheets, but if I remember right the layout tab name is always equal to the defined spool name.

So, all you have to do is edit your title block template, find the proper attribute and assign it a "Field" pointing to the CTAB system variable. Also suggest you make sure your FieldEval system variable is set to 31 to make sure just about anything will update that field value.