There is a large amount of evidence that indicates that Seleukid heavy cavalry carried shields, at least after the mid-3rd C. BC., yet this isn't reflected in the EB unit.

Also, in the unit description:

The successors kept this mold, but added mail reinforcement to the bronze armor at the joints before replacing it with iron and added felt and lamellar barding to the horses after encountering horse peoples that did the same.
Where does any of this information come from? And I'm also curious about the choice of barding for this unit. It looks extremely peculiar and unlike anything I've seen.