Atom,
not sure if this was addressed before: in case the heroes defeat more than 1 corrupted citizen, there is no option to track that change. Perhaps that is not that difficult to implement. Minor thing, no priority by any means.
Wrong thread man (also, I thought only one corrupt citizen at a time was allowed?)
There are only one changeling leader. So one corrupted Citizen per quest.
Unless he dies and then reinforces.