Movement Speeds

[Steppe Merc]

How did the EB guys address cataphracts in EB anyway?

In MTW cataphracts were done well, they were damned tough but that was traded off in slow speed and quicker fatigue (makes sense with all that armour), so faster but less uber cavalry were still useful. RTW with its limited horse models made any heavy cavalry other than cataphracts obsolete for the side possessing them as they were all the same horse speed.

Did EB add more horse models (i.e. a slower one for cataphracts) or some other means of compensating for the cataphracts massive armour?

Genuinely curious.

Well, there will be many types of cataphracts. Some have less armor than others, thus would be faster. They probably would be a bit slower than say Hetairoi, but they will be faster than infantry. But a cataphract would probably beat any other heavy horse on a head on charge.
So in short yes, the cataphracts will possess their historical strengths as well as shortcomings instead of just being another heavy horse.