FWIW, I contacted a friend at Bar-Ilan University and asked him about the term "Eve's fig" for banana, and here's what he had to say:
Anyhow, I had never heard the term "te'enat Havva" before; but checking the standard dictionary of Modern Hebrew, Hammillon HeHadash, by Avraham Even-Shoshan, I discover that the term as "an accepted name for the banana." Reuben Alcalay's The Complete Hebrew English Dictionary also lists it but calls it obsolete.
The word for fig is not plural but is the construct form which is kind of like a possessive case but on the possessed noun not the possessor.
