Those entries have no significance. Those entries show up in my system as well. You'll see a lot of Not Found entries for any operation you do. Usually, most of those entries have no significance.
You may try this if possible.
Download this REG file and save it to a folder named c:\reg\
Launch AdvancedRun (from Nirsoft) and start cmd.exe as TrustedInstaller.
In the TrustedInstaller Command Prompt, run:
- reg.exe import c:\reg\securityhealth.reg
- exit
This restores some essential registry keys used by Defender.