they somewhat fixed the darkhold post 1.19, you can't really run through it's entirety anymore, there are a few areas you have little choice but to fight your way through.
As for dungeon ideas, I'd love to see some imperial fortresses. I'd imagine them to be fairly high-tech in design and architecture, frighteningly advanced, and alien when compared to beastmen strongholds, or even the city states. They would be guarded by magitek-powered security systems (troops in battle armor, or other war machinery) It's already been established that the empire is a highly advanced nation of ruthless conquerers, and I'd love to see more of it.