Destroying the Chosen is a wise gesture, but you must attack them in the proper locations. With the absence of the Seekers, it is clear that the Watch can not scout as well as they.
Thus, accept some advice. The Chosen are most concentrated in the Bowels of the Machine currently, they attempt to close off a series of portals that have been opening in that structure lately to fend off an "invader" they fear.
While the invader is dangerous to anyone near-at-hand, creatures called Roachviles that have long dwelt in the Underdark, these things do not pose a great risk to the Dunwarren settlement. I should be happy to advise further for your attack.
I provide another warning as well, the Dark Fey are indeed entering your city secretly. There is a passage, often wet from their feet's passage still, it is on the north end of canal ward bridge. I could readily guide some Watchmen to find the location, it appears it was once closed off but now stands unguarded and re-opened.
I expect these reports were once sent by the Seekers, but with their absence, perhaps the Council is ready to hear a proposition from myself.
Lomil