If the events of The Empty Chair fit into the novel chronology,
Well, there are a few discrepancies, mostly pertaining to the planet Remus, but several elements of Duane's
Rihannsu books have made their way into the current novel chronology.
In the
Vulcan's Soul trilogy, the Romulan exodus from Vulcan and journey to and establishment of the twin worlds is for the large part consistant with what Duane established
The Romulan Way, right down to characters such as S'task and T'Rehu. Terise LoBrutto, the historian who "wrote" the in-universe
The Romulan Way, even has a brief name-drop.
I just write off discrepancies as such--
The Romulan Way was written from the perspective of a 23rd century historian researching Romulan history, and thus prone to a few inaccuracies.
Vulcan's Soul, however, was told from the perpective of the memories of one of the participants, and therefore, more likely to be accurate.
Also, Duane character Janice Kersarus (at, IIRC, a feisty 176) appeared in the SCE book War Stories, set during the Dominion War.
Other aspects of Romulan culture as devised by Duane have made their way into other recent works, most recently the
Enterprise "re-launch" books.