[Verginius Rufus]

One of the three languages on Darius' Behistun inscription (telling how he became king of the Persian Empire) is Elamite. So at least the writing used during that period has been deciphered.

"Parthians and Medes and Elamites" are among the people present in Jerusalem on Pentecost day who were able to understand the apostles in their own language (Acts 2.9). The Elamite language eventually died out but not until the Middle Ages, I think.

[SunkenCiv]

Old Elamite remains unread. The Elamite high king Chedorlaomer is mentioned in the Old Testament (Sodom and Gomorrah) — the name is believed to be a multi-layer transliteration of Kudur-Lagamar (”the servant of the goddess Lagamar”).