Janet,

I would suggest, as soon as you've created a fresh document with that template created in a much older version of Word, I would immediately do a "Save As" and make sure that the document itself is saved as a docx format that's currently in use.

If the recipients insist in having it in the old format, at the end do a Save As again, choosing the old doc format.  Unless you're doing something very unusual, in both cases of doing the Save As, you can ignore the message that formatting may be lost.  This only happens when the formatting in question exists in one version but not in the other, and all things related to fonts have existed "forever" in Word.

I wouldn't expect that even an add-on would be reliable here.  This is a reason why it is critical that not just individuals, but organizations, "keep up" as programs change.  It would take just a few short moments for whoever has that ancient template in dot format to open it in a newer version of Word, do a Save as to dotx, then replace it.

Backward compatibility simply cannot be maintained forever, and not just in regard to NVDA.  Using templates that were created in very long out of support versions of Word is just not a good idea and whoever's in charge of those needs to get off the stick and update them to match the Word versions (and there have now been many) that use the "new" dotx format.
--

Brian - Windows 10, 64-Bit, Version 21H2, Build 19044  

You can't crush ideas by suppressing them. You can only crush them by ignoring them.
     ~ Ursula LeGuin, The Dispossessed