The 122nd Fusilier Regiment did indeed push on to southern Serbia. In June of 1916 the Regiment was sent to Galatia in response to the June Russian offensive. x In that operation, the Regiment was severely decimated.
I evidently have three postcards from the same man allthough without scroll helmet, all stamped may to july 1917.
GMGA 232 is mentioned in the second Macedonia book from the Reichsarchiv
I have three copies and you are welcome to one.