Last year I contacted one of the old established ornament makers in Germany to see if they had any information about such items. They knew nothing. I'm sure there was a major house-cleaning after the war.
I believe the old school way of making glass blown ornaments was to produce two halves of a wooden mold. These were hand carved and in this case highly detailed. The molds were then coated with graphite to protect against the molten glass.
Another bulb of the era showing similar scalloping detail.