That's a bad example, cause the mime in Sapienza is quite a distance away from the mansion which means they won't be able to hear it and guard AI knowledge does not transfer over to civilians unless they see or hear some sort of firefight in the first place. If they do hear gunshots they will run to the closest guard and then those guards will run to the reported position, alerting other guards on the way.
I used a better example a while back. I guess it doesn't really matter if I spoiler it:
If you make Sierra Knox's car crash on the track, nobody reacts. Everyone just moves on as usual. I don't give a fuck, that's shit AI.