>>>Is the coptic church in Egypt is the reader of the Gospel of Judas?
No, the Coptic church doesn't use Judas. Judas had disappeared until
it was very recently published.
>>>Why Irenaeus challanged this gospel, and why, on the next, that
gospel must be translated in Coptic, from Greek?<<<
Irenaeus challenged the gospel because he was a heresiologist and
figured this book to be heretical.
Most of the Gnostic texts survive in Coptic because they seem to have
remained in usage longer (or perhaps more widely) in the Coptic
speaking world. Alexandria was a major source for the Platonized
Hellenistic religious structures we call "Middle Platonism" and "neo-
Platonism", and a number of closely related systems of thought
including the Merkabah of Philo, both forms of Gnosticism, Hermetism,
etc.. Greek was the language of the educated in Alexandria, but
Coptic could reach a wider readership. Therefore it is no surprize
that the copies that survive would be Coptic translations of Greek