This Couatl.LOG was created after using the offline installer.
Either you are not using the current version of the Offline installer, or you antivirus must have blocked it (even partially), because your log shows you are using an outdated version of the Couatl engine, which is not normally possible to get when using the current version of the Offline installer.
The Offline installer, being Offline, means you cannot use a previous version you might have downloaded, even a few days ago, because it's constantly updated to be kept in sync with all the smallest updates of the Live Update.
So, again, be absolutely sure you download again the current Offline installer, be absolutely sure you are starting that one, because the version of the Couatl engine included in the current version of the Offline, as of today, is 4.8.0.4251 but your log shows you are running the 4236 version.
If you sure the offline installer is really the latest version, it's possible your antivirus is blocking the update of the .exe and letting pass other non-exe files, causing a mis-match between files coming from different versions, which will cause all sort of problems. In that case, the usual suggestion applies:
- Configure the antivirus and be sure the completely Addon Manager FOLDER is added to the Antivirus EXCLUSIONS
- Run the latest version of the Offline installer again.