Cataphract camels as far as i can recall was used by the palmyrans,they were'nt really cataphract,or fully armoured but they were covered withsome sort of armour.Parthians relied on the arab camels of southern iraq(and later sassanids),though i don't know wether they were armoured or not.

Ok now i'm gonna nitpick on the roman units:

Urban Cohorts:Oh noesthe Elmos(AUM) are backThey seem like a really elite version of the legionnares,but is it historically correct?

Repeating Ballista:Good to hear the developers know about Herons inventions,the Chieroballista is the first machine gun ever invented

Roman Arcani:What are these?there is no discription but they sound like some sort of uber unit that will chop others into bits.

oh and btw the romans have alot of units compared to other factions..