Well, I used to wrapper to install Steam then I selected to run directly the CK2 exe. I also notice that if you have a second monitor plugged in, it crashes. For the rest I used it for hours without any problem. It works definitely better than the CK 1 complete that I bought for Mac!
Well to be blunt CK 1 does not even work properly on PC. The game design is one of the great achievements of our time but the execution is completely amatuer (they even misspelled 'Hedmark' on the map, for Christ's sake). Luckily they have after many years of waiting fully delivered on the promise of CK 1 in the form of CK 2, it is a real gem. However, they now really need to stop messing around and come out with the mac version so that I can install the DLCs and latest patch already. If I had accidentally bought the steam version and been unable to install it I would probably have already gone completely bananas by now waiting to play the game.