I really like the rules for generating adventure sites, they are quite comprehensive and cover off most of what a gm will need to know. However, the tables for dungeons and castles don’t really cross over with the rules for strongholds (except for a side bar explaining the difference between a castle and stronghold), which is strange as players may decide to take over any random dungeon or castle and make it their own.
The main thing that is missing is a reference to the number and type of functions that might be found as part of one of these adventure sites. At the moment is something the gm will just have to make up on the fly, without a corresponding table to roll on.
My suggestion would be to include a table of working functions, modified by the size, purpose and condition of the castle or dungeon. This can then be the basis for what the players find as they explore and then decide to make themselves at home.