Yes, you can add those attribute to the ones Unraid monitors, so will get notified if they increase.
You can clear those by rebooting or clicking on "clear stats"
The Asmedia controller you're using is a 2 port controller with SATA port multipliers, these are known to have multiple issues, you should replace it with one of the recommended controllers.
In the syslog it's also log as a disk problem, what you can do for WD disks is to monitor these attributes:
ID# ATTRIBUTE_NAME FLAGS VALUE WORST THRESH FAIL RAW_VALUE
1 Raw_Read_Error_Rate POSR-K 200 200 051 - 70
200 Multi_Zone_Error_Rate ---R-- 200 200 000 - 0
Ideally both should be 0, when they start climbing is a bad sign, and if they keep climbing you'll likely going to run into more issues in the future.
There are some known issues with v6.9 and the ST8000VN004 when connected to an LSI, if it's an option you can connect them to the onboard SATA ports, otherwise best to go back to v6.8 for now.
Yes, that what was happening to the other users, shutdown time-out was set to more than 30 secs but Unraid started forcing the shutdown almost immediately, after just a couple of seconds.
Diags saved on the flash drive would confirm but there have been a couple of reports where it looks like the shutdown time-out is not being honored, i.e., Unraid forces the shutdown after a couple of seconds even if the set time is much higher, changing the setting (Settings -> Disk Settings) to re-apply it fixes the issue.
XFS (md9): Filesystem has duplicate UUID 5cbc417e-05c1-46d6-8b6f-e54881ce73f4 - can't mount
This usually happens when the disk is already mounted by UD or manually.