Oh well! I just find it a little funny that the pagans allowed me to keep my land. It was my fellow christians who stole it from me.
Post a bug report. (regular) Holy Wars let people of the right religion keep their lands, so the same really ought to happen with crusades...
It was a catholic crusade, though, and my ruler was orthodox. I figured that to be the cause, or is that wrong?
I believe all Christians get to keep their lands even if they get crusaders. Basically they pay a big fine to the Pope at the end of it.
If you try and crusade the pagan nations, they very often change to Christianity just to keep their lands.
Edit: Here's a picture of my ironman game. I'm Empire of Gods, house Karling.
Can see quite a lot of new features. For example, check out all the lands the Teutonic Order has all over the place. Christians in general are superpowered now with all the buffs to Christian holy orders and the ability to take out 300g loans at whim. Also, if your family owns the holy orders (in this case, the Karling family is in charge of Teutonic Knights as well as the Knights of Santiago) you get to hire them at a massive discount. You can even call them into war with you! Christians can also get two more additional massive buffs to character relations in the form of pilgrimage (permanent +5 for everyone) and donation to the Teutonic Order (permanent +10 to every priest). This makes running the empire even easier. Marriage also gives +30 relations to the parties involved.
You're also considered allied if you're the same culture now too, which is interesting.
I haven't been able to figure out how the cardinal system works though. And the pope constantly pesters you to switch to papal investiture which is complete bullshit anyway.