Thank you, NevB!
That possible-Schweig-Müller-figurine was just for comparison of size - here's another photo showing her aside the Brockwitz-Lady including frog...
The second photo shows a group of three amber figurines which are all similar in the making of that huge green one. In my opinion these were made much later than 1930s, probably even 1960s
Regarding the considerable stress crack the green lady suffered, my friend is wondering whether perhaps it sat on a lamp-base with a too strong and hot bulb.
Anyhow, there must have been more of these around, and we loved to hear further opinions - thank you!