How can I help the AI make the unit I intend it to make

I am making my own version of Barbarossa campaign. Mostly changed civilizations in 1, 2 and 4. In 2, I actually keep the civilization of Poland same internally, just for the siege discount and the incentive for infantry.

Next I replace all the Castles with Kreposts (I thought it will be easier than disabling Boyars at Castles) and added Huszars and Leitis at Kreposts. The AI makes only infantry and siege. Any idea how I can incentivise it to make Leitis (good against Teuton Army)?

There are two ways:
1)You create the units you want using cycled triggers;
2) You create a custom AI. It’s very simple, there is a tool on this forum called AiBuilder.