This is what fixes it for me every time
The useAirportCache=0 line is not the problem, because this is how it's supposed to be, this is how it is by default, and it won't make any difference even if the line is not there in the first place.
I think the real issue that is making you *think* editing the file has fixed this for you, is the other line, the logfile line. Since there's no path, the log file will be created in the current working folder for the Couatl engine. But the current working folder might change if you have the Couatl engine started automatically by the sim (normal case) or if you start it manually, so it might be better to set a path for it, so it will never change.
However, since you not always need log, and the airportCache is disabled by default, you might just remove the Couatl_MSFS.INI file.