Quote Originally Posted by NerdyKris View Post
The only page of the diary we've seen, if I'm not mistaken, was written during the adventure, while they were just sealing the gates. It might not include the details of how they built the fortresses, Xykon might have simply deduced that from the fact that they'd already seen two such fortresses when he said that. There might very well be a diary that includes the details of Kraagor's gate (especially if she needed to entrust it's care to someone after her death), but it's separate from the book Xykon found.

Xykon was also only able to find the location of one gate when decrypting it the first time. They had to go back and decrypt the other three after failing at Dorukon's gate. Which means it might also just be a matter of Xykon and Redcloak not having bothered to decrpyt that passage once they had the remaining gate locations, especially since the first two gates they arrived at were fairly simple in their defense. They might not have realized there's a twist to Serini's plan, since they haven't run into any before.
The thing is, we know much of the diary is probably not encrypted, so Team Evil had reason to believe that whatever that is should be important, so I would not assume any information of that sort was left alone and unnoticed.