I downloaded the mod off Dropbox yesterday. I've gotten two "Bandit Ambushes in Cities" , one in Rome and one in Massilia, and both times only one bandit appeared. I ran around both cities looking for the other two bandits, but couild not find them.

I just triggered one in Cyrene which does not use the Roman Scenery and it worked fine.

Perhaps in the Roman-style cities some of the bandits are spawning inside geometry?