If the tactics issue is solved for Cataphracts then they easily become one of the best retinues in the game again. They always absolutely obliterated AI armies, the only issue was the tactics selection would cause them to suffer atrocious casualties in the process. You'd usually lose close to half the retinue due to firing tactics that were completely useless to you and were easily countered by AI tactic selection. With Embolon improved the only AI that I can honestly see fighting evenly against a sizable pure Cataphract army would probably be the Mongols, and they can be dealt with because Crushing Charge will fire and immediately move the Skirmish phase into the general melee, which will wipe the floor with the hordes.