You might want to change the Rta Pa (heavy cavalry) of the province defense into normal Bhödpa Horsemen. I tried taking their home province with Black Knights of Ulm, but they couldn't break through the horse-archers... I don't think any other nation gets knight-quality cavalry in their PD.
While looking at the Rta Pa stats, I also noticed that their head protection doesn't look right. Their head protection was halved, and then when looking at the cavalry commander I found the problem - they had two heads but just one helmet!
You've used wrong #itemslots value. I think it was wrong in the modding manual, at some point.
You'll have to change all four cavalry units. While doing that, you could fix the Yack Rider gold cost (you said that it was a typo, but didn't change it in the update).
The mod creates an unused Breastplate armor 250. Is there a reason for it?
The Rta Pa cavalry have unexplained natural protection of 5 and all-around awesome stats. After the itemslot fix, they will have protection 21 (20 head/22 body). I think it's a bug, since they'll have very respectaple prot 18 even without it.
Rta Pa unit and commander have few minor differences between them. I think the units are supposed to have enc 4 and Falchions like the commander, but they currently have enc 3 and broad swords.
Finally, it'd be nice if you used the #version x.yy modding command in the next version.
This is a great mod, and I hope you have time to fix the small problems left in it.