It really is incredible that the Crusade managed to succeed. Speaks volumes of how badly managed the Turkic government was to let that collection of chuckleheads even make it through Anatolia.
I always thought it would be cool to have a Crusade mechanic that incentivises personal glory ahead of the needs of the Crusade as a whole. Maybe add unique plots/goals to discredit or disrupt fellow Crusaders in hopes of appearing the most virtuous, as was the case historically. I know this is somewhat represented by having the top contributor having their beneficiary rule the new Kingdom, but some other reperesentation of the intrigue, self interest, and proto-nationalism elicited from the Crusades would do a lot for immersion.