🚀 go-pugleaf

I meant create a text frame, type into it whatever it is you want to appear in the index (TOC) using a unique paragraph style, then open the Attributes panel and set the frame to non-printing, and finally, group it with the ad (they should be in close proximity -- one on top of the other, for example, with left edges aligned, as the TOC feature reads down the page first, then moves right and reads down again, though that may not matter in your case).

I'm not a scripter, but a TOC does what you want to do, i.e. it gets page numbers for every occurrence of any paragraph style you include (hence the unique style for the ad tag frames), and it can be updated easily when you move things.

Peter