Very interesting work.
Again, though not declaring any personal claim to Christianity myself, I find the "invention" of Judas Iscariot unnecessary.
The mythology of the gospels aside, the rabbi known as Jesus of Nazareth was destined to crucifixion, no matter what as the priesthood of the time had no sympathy for messianic pretenders that publically embrassed them while creating powerful movements consisting of sympathic followers. Rome likewise did not appreciate anyone calling themselves "king" in opposition to Caesar, and this self-proclaimed rabbi had might as well fashioned his own cross and asked his apostles to nail himself to it after congratulating Peter for identifying him the Messiah, King of the Jews.
Another character, like Judas Iscariot, handing him over as a betrayer is an invention? Unlikely. Judas is actually just the name "Jude," which was slightly changed so as not to confuse it with the name of the brother of Jesus who is also named Jude. (John 14:22) There is also the prophet named Judas Barsabbas mentioned in Acts 15:22-33.
Then, whether or not this is the same Judas as the "brother of Jesus" or someone merely writing in his name, the Epistle or Letter of Jude is actually written by someone named Judas--but since "Judas Iscariot" is supposedly the betrayer, Christians changed the name of the author to "Jude" to avoid confusion.
While I do know that the prophecies supposedly fulfilled by the betrayal of Judas Iscariot are merely midrash attributed after the fact, it is unlikely that someone with the same name of the "brother of Jesus" who helped to betray him to his death--an embrassing fact--is entirely invented. There would be no reason to change "Judas" to "Jude" in the title of the epistle, especially since scholars believe it is pseudonymous--and that would make no sense if we are talking about a character made up of tropes harvested from the Old Testament.
Why hide a "made up fact" you worked so hard to make up? You would want people to see what you worked so hard to make up, wouldn't you?
With or without Judas in the gospel narrative, Jesus of Nazareth always marches to his death. Why invent such a character with a name of the brother of the person who betrayed him--and then change the name of the innocent brother?
But it doesn't matter to me in the end.