All right, so my group has been playing this scenario, and man or man did it go pear shaped for them. They missed most of the important clues, and took the one from the refugee and when off into the woods. Suffice to say the cavalcade did its job and moved on unmolested.
I did have them come upon a group of beastmen helped out by a plague bearer and beast of nergal that they had to deal with. though the gold wizard died from disease that following night.
The cavalcade though, and ideas on how to deal with its unmitigated success? I think they want to rest up a few days and then go hunting for it. How about the spread of the disease and the plot against the shyllans. I never expected it to get to this point, so I'm not entirely sure what to do with them now.