In vanilla, a bug in combat tactics has their troop mix have a tendency to trigger the tactics "Harass", which gives a hefty bonus to light cavalry stats (which aren't part of the retinue) and penalizes horse archers (which are in the retinue) or "Raid," which gives bonuses to light cavalry and light infantry (neither of which are part of the retinue), instead of the more useful "Swarm." It's all because Paradox made Horse Archers count as Light Cavalry in tactics selection, which has them occasionally choose extremely sub-par tactics. I'm not sure if this persists in EMF or not, because when I'm playing the Byzantines by the time I'm fielding Cataphract armies I have close to 10k of them simply obliterating levy armies because of the Crushing Charge tactic, which forces the Skirmish phase into Melee and absolutely slaughters the piss-poor units the AI fields.
As for Embolon Charge Formation, I'm not entirely sure what could be done to make it better. In vanilla, it's half as good as Couched Lance Charge, with a 240% bonus to Heavy Cavalry compared to 420%. It gives bonuses to Light Cavalry, when it'd probably be better giving bonuses to Horse Archers offensive stats. Maybe something like 360% stronger Heavy Cavalry, 150% stronger Horse Archers, -120% Heavy Infantry. Basically, though not as strong as the Couched Lance Charge or Retreat and Ambush tactics individually, it combines their two signature bonuses to make Cataphracts function a little better.