Greetings Doves & JOVIALTo the best of my knowledge many pseudepigrapha (which means "false/incorrect" TITLE - I don't thing the nomenclature is making any claim on the veracity of a particular work's content, but rather it's TITLE/ALLEGED AUTHOR).
As far as I know most pseudepigrapha (http://www.pseudepigrapha.com/) are dated in the 2-3rd centuries BC. I can recommend a very good book which has many references to the Apocryphal, pseudepigraphal and Targumic works: "The TRINITY" by Dr. Robert Morey; ISBN: 0-529-10692-2. It may be out of print but you might be able to get a copy on E-Bay.
Regarding the Dead Sea Scrolls (DSS), I no longer have my book. It was about 8 years ago when I read the entire contents of the DSS. If I recall correctly the author's name was F. Garcia Martinez. I'm pretty sure he had a swection called "Liturgy of the tongues" (plural). I canot explain the descrepancy between your volumes and mind except to say that the taxometric classifications of which cave, which column etc might be now uniform, but each scholar may have the lattitude to title the fragments they were working on with their "own titles". But my best recollection was that tounges was in the plural and if I remember correctly it was accociated with Moses and the anointing of the 70 elders as judges to help Moses judge Israel.
As fas as 2 Esdras (= 4 Ezra) 7:28-32, I took it from the KJV authorized Version with apocrypha (http://unbound.biola.edu/).
As to its exact wording the farthest I could track it was to Jerome's Latin Vulgate Bible.
BLESSINGS TEFE