I would agree that it’s unlikely that the house settling is causing the problem. But you’ll know if you switch to a different type of automation so that’s worth a try.
Just be aware that there are a few significant differences between smart home monitor, which is an official feature, and webcore, which is not. These might not make any difference to you, but you should just be aware of them.
One) only smart home monitor alerts can be used to trigger the scout alarm system if you are using that integration
Two) the smart home monitor alerts are eligible to run locally if the devices are eligible to run locally. It’s a little complicated, because some parts of smart home monitor, including arming and disarming the system, don’t run locally. But if you are using a zigbee door sensor to trigger a Z wave siren or some lights and you have set that up with smart home monitor, that would still happen even if the Internet was down.
However, no custom code is eligible to run locally at this time. So if your Internet is out or just if the SmartThings cloud is not available, your custom code, including core or web core, will not run at all.
Again, that may not matter to you, but it’s just something to be aware of.