I got to thinking (that is amazing)

have you tried the KM forum on forum.axishistory.com

join up and ask if the unit your father was in is listed in the Freiburg BA/MA RM listings

you can obviously see that English is the preferred language. At the time I am not at all sure if # 59 is the header for the KTB listings which include FLAK of the KM. It does includ though the KTB for the S-boot flottilles and other shipping

Erich ~ good hunting !