While SO might fit Tatars, I don’t know how it helps when the gold is low. SO is 1000 gold upgrade and making 7 more onagers is better in most cases. Steppe lancers with cav archers should also be able to deal with halbs skirm ram. SL even in their current form fare better than hussars against halbs with the range.
I don’t think giving them chain mail is a right option since its their identity. Either try to win in castle age with your power spike of xbows/cav archers and prevent them getting to halb ram economy or the lancer+cav archer option
he mentioned siege rams, scorps are hard countered by rams
HScorps are hard countered by Siege Rams, but HScorps + Hussars are not.
Tatars get Siege Engineers, so they can use those +1 Range HScorps to clear away the Halbs, and then use the Hussars to destroy the Siege Rams, which are too slow to reach the HScorps in time to deal any real damage.