Horse Archers and how the AI Cheats. What do you do?

Playing an EB 1.1 game as Baktria and of course the Saka are constantly coming down and slamming me with wave after wave of horse archers.

I have no problem killing them I can get them into combat but that is almost impossible.

Why?

Because the AI cheats plain and simple and it is annoying as hell. Lets say the AI has 4 units of HA lined up firing away. I send in my cav charging at one of the units.

Basically the AI cheats and uses the fact that it knows which unit I clicked on to have just that unit fall back and retreat while the rest of the units just sit there happy as can be still firing.

Now I know the AI uses this with every unit but it really overbalances the horse archers with their range and speed.

So how does everyone deal with that?

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Also have a second question. Does the computer not account in any way shape or form for line of sight?

Fighting the Saka I have had multiple times when the entire enemy army is out of line of sight on the other side of a forest but still in arrow range.

So what happens?

Not only does the AI easily target and fire at me but somehow can also target my most vulnerable units without problem. So I have 3 units in range but on the other side of a forest, 2 are hoplites and one is a levy spear unit. Of course the entire Saka archer force can perfectly target my levy spearmen and decimate them.