I have also managed to resolve the error 5 and get the Sim to install.
Steps taken
Turned off antivirus during update
Checked language pack
Reinstalled the redists
Deleted everything
Ran a registry checker i use ccleaner
Updated all drivers on my system and any MS updates
Installed the localcache on a SSD not my M2 system drive
It may be that when Installing or upgrading where it fails it corrupts a file. Just starting the update from that position breaks it with constant errors and ctds
I can’t say for certain but the above worked for me.
Currently flying the A320NX mod and its smooth and so far ctd free. Yay