Well I don’t have much information about them, really. But I remember to see a thread here that gave some explanation about them. It was provided by Dan Gurden. Attention! Be warned that it includes spoilers about Nemesis You can find it here
I also think that, to a certain extent, we can harmonize discrepancies between cannon and the Way of D’era. If we consider that the movie is done under the perspective the Federation, then not all information given in the movie is necessarily true. After all, Romulans like to keep their business private, and misdirection is as likely to be used as simple and plain concealment of the truth.
We come, we are not seen, and inevitably, we conquer.
First and Last, there is Duty.
Romulan Proverbs