One thing is, that Linked Clad Cavalry should still not be so easily attainable (same for Battle Wagon (not the Horde one!)) and Far East Celts shouldn't start with it maybe? They still have a lot of good units, even in the beginning of the game.

And other thing - what is Quest Campaign? I never seen anything like that anywhere in game, nor in readme - i just start the Anti Imperial Campaign, and start the script as you suggested (with adviser X, after show me).