I think I found an inconsistency, don't think this has been mentioned before.
In chapter 8 of TUC, Proyas thinks back on the murder of the line of Nejata:
"Where, Father?" he had asked after hearing the last of House Nersei’s ancestral rivals, the Nejati, had been executed. "Where lies the honour in murdering children?"
If his father had spared the sons of Nejata, what then? Vengeance would have been their inheritance, discord and rebellion the consequence.
But, according to the TTT glossary:
Nersei, House—The ruling House of Conriya since the Aöknyssian Uprisings of 3942, which saw the entire line of King Nejata Medekki murdered. The Black Eagle on White is their device.
In the TUC glossary the date of the Uprisings is changed to
3742, but the rest of the entry is identical.
Anyway, the fact remains that Proyas could not have been alive at the time the line of Nejata was extinguished. One could argue there
could have been descendants of Nejata alive in Proyas' lifetime, but it seems very unlikely from the wording in the House Nersei entry.