Elisabeth Platzer is not my grandmother, as I first thought. But she is listed as "Bree" in Index of the Jewish Records of Vienna:
"
No. 4502
Year 1867
Numerative 2365
Code 1
Volume Wien
Last Name Gostl
First Name Adolf
Parents/Annotation Bernhard/Bree Elisabet
Last Name
First Name
"
AND
"
No. 292823
Year 1881
Numerative 2231
Code 1
Volume Fünfhaus
Last Name Gostl
First Name Stefanie
Parents/Annotation Bernhard/Bree Elisabeth
Last Name
First Name
"
AND
"
No. 98413
Year 1869
Numerative 2366
Code 1
Volume Wien
Last Name Gostl
First Name Gisela
Parents/Annotation Bernhard/Bree Elisabet
Last Name
First Name
"
But this data might be mistaken, so I won't list then on Geni as children of Bernhard/Elisabeth Gostl.
Also it seems that "bree" is not actually a word in any European language I looked at, but it is a name or nickname. So without any of her actual documents, I have no idea why Bree would have been in her name.
Any other ideas?