I have checked his name on the German wargraves website but I didn't find a possible match and honestly I think this is where it ends.
My estimated guess is that he was reburied, mayby in his hometown and that he thus isn't listed on the wargraves website (the list isn't there isn't 100% compleet), this grave marker from his first grave most likely would have been kept as a kind of souvenir, this isn't an uncommen tradition in Western Europe.
P