Thanks for posting this, it is very valuable for the N54 community. The engine internals looks like shit considering the low mileage but being punished on the Nurburgring accelerates the wear. Perhaps the oil system has starved during hard cornering? That may explain the abnormal wear on the crank journals. The cylinder walls may be scarred by carbon from the upper part. In case the piston had swelled and scarred the walls you would easily see this on the piston skirts.
Strange that the #5 piston is so beaten and also that the crank look so bad. I guess the combustion chamber with a lot of oil in it is # 5, right? It appears that one of the intake valves in this cylinder may leak oil by the shaft.