L'RELL is possibly the new Chancellor of the Empire, yet Ateztbur was said to be the first Klingon Chancellor, wasn't she?
I am probably mistaken.
STVI:TUC (circa Nov. 1991) was already inconsistent as in the 4th Season TNG episode "Redemption" (circa June 1991) had Gauwron stating: "Women cannot serve on the Council."

(To be fair though, it could be a case of Klingon's re-writing history because of what happened when Klingon Women served on the Council previously so the fact females HAD served was erased and the rule changed. Also, nowhere was it said in STVI:TUC that Ateztbur was in fact the first female Klingon to head the council; just that she was named in her father's stead after his assassination to lead the Council.)