An additional point: TFR follows the timeline of The Star Trek Spaceflight Chronology,
which at the time was the nearest thing to a historical Trek
timeline. The Federation ships and many of the events were outlined in that book, which Ford then fleshed out for use in the story.
And lets not forget a vote of appreciation to authors in the current "era" of novels who have folded items and concepts from TFR back into the "modern" Klingons (the version that evolved through the TOS movies/TNG/DS9/VOY/ENT depictions.
Heck, even the TFR name-honorifics have been used as recently as the Vulcan's Soul