I am working on some changes to how monsters on Dwilight work right now, based on conversation with Vita and Andrew on IRC.
The general thrust is this:
Monsters on Dwilight will be strongest within the greatest concentration of rogue regions. (Right now, obviously, this is the West.) Monsters coming from there will be stronger and smarter than monsters spawning elsewhere.
Please note that the "stronger and smarter" means, at least for now, that those monsters will be like the monsters you have been seeing, and monsters spawned outside that area are being nerfed.
Additionally, due to the way we will be representing "smarter" (since there was no differentiation in the past), all existing monsters, however strong they may be, will be considered "dumb" monsters by the game. They will continue with whatever goals they have right now, but then will exhibit classic monster behaviour: wander randomly, break stuff, eat peasants, occasionally start a TO.
Furthermore, the presence of civilization will itself have a taming effect on the monsters, a halo of sorts that will weaken monsters that spawn within the closest few regions to human realms.
A consequence of this (that we would be happy enough to have you "game", since it fits with any reasonable IC explanation for why the behaviour exists in the first place) is that if you can split up rogue areas, and cut them off from the main bulk of rogue regions in the West, you will make life at least somewhat easier for yourselves. So for instance, if Westgard is able to take and hold Ygg d'Razhuul, that will prevent smart monsters from spawning in any of the rogue regions between them and Arnor.
I'm nearly finished writing these changes now, and expect them to go live later today—most likely either just before or just after the sunset turn change.