While in build screen it uses Ancient Cavalry graphics, unit animations and civilopedia use Keshik graphic.
Shouldn't all of them use Ancient Cavalry graphics?

With maybe exeption of Sassanid Immortals (Keshik animation kinda fits there).

Which scenario is this? Do you have a save file? Can you give steps to reproduce? (i.e., like what civ(s) to look at)

Fall of Rome.

Steps?

If you start with Sassanids you'll see that Immortals use Keshik graphics. And Immortals are just renamed Heavy Cavalry.

If you check in civilopeida, Heavy Cavalry indeed uses Keshik graphics.


But, just get tech for a Heavy Cavalry and you'll see that Ancient Cavalry image is used in city build screen.


Personnaly, I don't know which is one is intended, but to me it sound something similar to Cataphract using Raider art in Middle Ages (which was FIXED in 1.12).