Ok. I've now experimented doing exactly what I described above.
I used Audiograbber to rip the first two tracks off of a CD that is inserted. I erased the otherwise obtained correctly data about the CD, and created a "Test Artist" and "Test Album", with "Track 1" and "Track 2".
I then opened MP3Tag pointing to the \Test Artist\Test Album folder, and as expected the two tracks are there.
I then selected the two tracks, and let Audiograbber do its thing. It created the two tracks in the specified target folder.
I then went to MP3Tag and opened that folder. I then selected the two tracks, and clicked on Tags Sources. And now sure enough the FreeDB and local FreeDB items were no longer grayed out. I selected "local FreeDB" where my newly created 6/1/2020 local Windows-form database now lives. I was presented with a dialog where I clicked on "develop FreeDB disc ID from inserted CD" and pushed NEXT.
Apparently this worked, and I then was presented with a multiple-choice selection dialog (as this CD exists in FreeDB three times):
I selected the first one, and then pushed the PREVIEW button:
Looks good. I then pushed NEXT and was presented with the retrieved information from that FreeDB DISCID entry now inserted into the corresponding tag fields, as well as matching up against the track list. I didn't know what to do now, but simply selected the first two tracks on both sides.
And then I pushed OK, and apparently all of the tag data was correctly assigned to the corresponding fields of the tags in these two tracks. As I suspected, everything in the tag fields was populated, but the external file name was left exactly untouched.
So I would now than use CONVERT -> Tag - Filename and set it up to rename the files to match the title, or whatever.
Ok. I would naturally NEVER use this workflow. I have Audiograbber and all of this would be done automatcally at the time of ripping, not after-the-fact here. Audiograbber has access to FreeDB online, or local FreeDB database offline. And now it has been updated to recognize the death of FreeDB, with the latest 2020 version now accessing GNUDB which is the natural successor to FreeDB. But I believe GNUDB has the same data, and possibly the same data issues as FreeDB had.
Or, I can use EAC which uses MusicBrainz as its successor to FreeDB. MusicBrainz is more robust and accurate than FreeDB/GNUDB, and contains more data per CD. But it requires that the client program be modified since it's not the generic universal FreeDB Protocol query that must be used, but rather the proprietary MusicBrainz client interface.
Anyway, I think I now understand what this MP3Tag functionality is all about, and how it works. I would, of course, never use it. But I've now learned all about it.
Thank you very much for the guidance.