This document dated 2017 was posted over on golfmk7.com in 2017;

Not sure if this is an entirely different issue but I’m assuming it probably isn’t. The service action document refers to possible stress fractures at the corner of the steel reinforcement plates. Presumably these reinforcement plates are what provide support to the outer plastic frame surrounding the tilting / sliding pano roof. When the steel plates expand or contract in warm / cold weather, then presumably the outer plastic frame doesn’t have the same expansion / contraction properties, the result being the cracks that some owners have experienced.
The purpose of the service bulletin is to provide USA dealers with a fix for water leak prevention, so this could also be a risk for anyone with visible cracks in the plastic frame.