Uninstall and reinstalling will not have any effect, dnd so "registry cleaning. If an .ERR file is not created with Logging enabled, it means there was no error OR the error was caused by an EXTERNAL cause, most likely another program interfering, so the program couldn't even access the code that writes the error log.
The error log cannot contain problems caused by other products, it will only contains errors in the Python engine language, that happens inside the Couatl.exe program, because it REALIZED there was an error. Error caused by interference by other products, such antivirus or other invasive executables (maybe not even related to Flight sim) cannot be logged.