You are correct that they are not Austrian. My mistake. I originally thought they would be Austrian but I later found out that they are Czeck and I didn't remember to correct it here. Sorry for that. Your estimate was better than my original one and close. Your estimate of the age sounds accurate.
Attached the Czeck silver hallmarks from the 20th century.
GOBEL probably is a local producer in Czeck which I have not been able to find.