Wow! Sorry to hear that. Because it creaks only when my vehicle flexes, it's not bothered me enough to look into correcting it. I assume it's some interface meeting somewhere that would need to be lubricated or weatherstripping replaced, etc. Obviously, you have put effort into and not found a solution. That's not great news for my future with this car. I've read posts about problems with the sunroof but seems I remember most of them had to do with not closing correctly or rattling, etc. Are there posts talking about the creaking and to the level you're experiencing with any solutions?
2014 SXL, only mods are after market rims due to recall.