@Bwian,

Good question, which is "meeting code" for I don't know the answer.
bone_pelvis or bone_H_saddle are the root bones for humans and horses
respectively, but the animations I've look at for humans just move them
forward, I haven't looked in detail at the horse's

fs_horse_stand_a_turn_90_cw_1.cas

animation which is one of the only "turn" anims I see.
I think you are right that if you animate a turn about the root bone
in the default horse skeleton, the following chariot structure
might "skew" unrealistically.

That much said, even if you pivot about the bone_H_saddle bone of
your chariot is it bad in the viewing or do you just think it might be
bad. I don't really know an answer to this; i don't want to advocate
a solution whidh make existing animations invalid since that just makes
more work for the animators (you).