If the A350 is similar to other Airbus aircraft composite bits such as wing to body fairings etc. the mesh is embedded into the upper gel coat so I would assume that the production process is as Widgeon has described.
There are repair procedures for repairing the mesh, but these are for fairly minor parts such as fairings. I've never worked on a A350 but I would assume there must be some sort of repair scheme for minor damage.
I think in this case it must be large area or several large areas that need repair if Airbus haven't figured out how to repair it yet.