I have been thinking about the fortifications of a Karak. My thought process has been hung up due to the warhammer world having a weird conglomeration of weapons. Fortification is essentially an outgrowth of weaponry and vice versa. The existence of muzzle-loading cannon and muskets puts the technological advancement of weaponry at an approximate 14-16th century mark for an earth equivalent, and the existence of a rifle puts it closer to the 17th to 19th century.
Obviously, this spans several major periods of architectural design for fortification. My general thought is that warhammer would be best suited by treating it as a kind of transitional period, where the new weapon technology is somewhat ahead of their engineering, but defensive architecutre is beginning to catch up. That being said, it would also seem to me that dwarfs, though staunchly conservative, would be on the cutting edge of defensive engineering.
This is best reflected by Italian schools of castle building of the early 14th century where, aside from keeping certain features specifically suited for pike infantry and archers, their technique was roughly equivolent in engineering level to the fortifications of central Europe three centuries later. What I'm getting at is that it is historically valid that small talented pools of engineers can effectively produce fortifications centuries ahead in form while the rest of a region takes years to catch up.
This is kind of how I see the dwarfs. Their tendency to live underground is actually already a technique that wouldn't be fully developed in European defensive works until the development of the Maginot Line after WWI, whis is early 20th century. Basically, to resist cannon, free-standing walls have to be backed with earthenworks and the overall profile of a fort has to become lower rather than higher. Eventually, strongholds were completely brought undergound into bunkers. A Karak is essentially a bunker. So could Dwarfs have already developed defensive techniques that correlate to bunker defense (historically 19-20th century)?
In designing a Karak I have already given it, effectively, a two story bulwark wall, and barbican, and also interior defenses such as mines and collapse points. Would they have already considered angles of fire and developed outworks specifically to take advantage of the level trajectory of cannon fire and muskets? Basically, what period of engineering proficiency are we talking about? Has there been a dwarven Vauban?