[jecilop]

Thank you, @chaley.
Tested and working. That was far simpler than anything I was coming up with!

Next hurdle: Do you know a modification I could make to the Save to Disk "save template" that would force this also? I already having it printing the words using {#words:|(|words)} in case none are generated/exist for the type of entry.
I tested it after the comma 'fix', but it definitely isn't based on the appearance in Calibre - just the hard data.

Whoops!!! Turns out doing this affects using that column in a math function. Once the comma format is there, the simple math function (generating a custom page count) stopped working and returned an error.... Arrgh..

I'd still like to know if I can force the comma to show in the save to disk template "tag".
Interestingly, the comma shows in the book metadata jacket as desired when this code is applied. The tags or references are the same so it's curious that one shows commas and not the other.