It’s the first time I heard what those books say in advance about Christ and Elijah.
But the essence of those prophecies is very similar to what is already in the canonical Hebrew scriptures. So could it be that the writers of those non canonical books based their writings on those that already existed and just paraphrased what the inspired God’s prophets already had written?
To my knowledge the Christian Greek Scriptures almost exclusively quote from the canonical Hebrew scriptures. Maybe that was an important criteria in deciding what Hebrew scriptures should be included in the Bible?
So here is what God’s true prophet Isaiah wrote in advance about Christs sufferings:
So here is American Standard Version:
Isaiah 53:1 Who hath believed [a]our message? and to whom hath the arm of Jehovah been revealed? 2 For he grew up before him as a tender plant, and as a root out of a dry ground: he hath no form nor comeliness; [b]and when we see him, there is no beauty that we should desire him. 3 He was despised, and [c]rejected of men; a man of sorrows, and acquainted with [d]grief: and [e]as one from whom men hide their face he was despised; and we esteemed him not.
4 Surely he hath borne our [f]griefs, and carried our sorrows; yet we did esteem him stricken, smitten of God, and afflicted. 5 But he was wounded for our transgressions, he was bruised for our iniquities; the chastisement of our peace was upon him; and with his stripes we are healed. 6 All we like sheep have gone astray; we have turned every one to his own way; and Jehovah hath [g]laid on him the iniquity of us all.
7 He was oppressed, yet when he was afflicted he opened not his mouth; as a lamb that is led to the slaughter, and as a sheep that before its shearers is dumb, so he opened not his mouth. 8 [h]By oppression and judgment he was taken away; and as for his generation, who among them considered that he was cut off out of the land of the [i]living for the transgression of my people to whom the stroke was due? 9 And they made his grave with the wicked, and with a rich man in his death; [j]although he had done no violence, neither was any deceit in his mouth.
10 Yet it pleased Jehovah to bruise him; he hath [k]put him to grief: [l]when thou shalt make his soul [m]an offering for sin, he shall see his seed, he shall prolong his days, and the pleasure of Jehovah shall prosper in his hand. 11 [n]He shall see of the travail of his soul, and shall be satisfied: [o]by the knowledge of himself shall my righteous servant [p]justify many; and he shall bear their iniquities. 12 Therefore will I divide him a portion with the great, and he shall divide the spoil with the strong; because he poured out his soul unto death, and was numbered with the transgressors: yet he bare the sin of many, and [q]made intercession for the transgressors.
And for comparison the New World Translation: (Can you guess why I prefer this chapter according to the NWT?)
Isaiah 53:1 Who has put faith in the thing heard from us? And as for the arm of Jehovah, to whom has it been revealed? 2 He will come up like a twig before him, like a root out of parched land. No stately form does he have, nor any splendor; And when we see him, his appearance does not draw us to him. 3 He was despised and was avoided by men, A man who was meant for pains and was familiar with sickness. It was as if his face were hidden from us. He was despised, and we held him as of no account. 4 Truly he himself carried our sicknesses, And he bore our pains. But we considered him as plagued, stricken by God and afflicted. 5 But he was pierced for our transgression; He was crushed for our errors. He bore the punishment for our peace, And because of his wounds we were healed. 6 Like sheep we have all wandered about, Each has turned his own way, And Jehovah has caused the error of us all to meet up with him. 7 He was oppressed and he let himself be afflicted, But he would not open his mouth. He was brought like a sheep to the slaughter, Like a ewe that is silent before its shearers, And he would not open his mouth. 8 Because of restraint and judgment he was taken away; And who will concern himself with the details of his generation? For he was cut off from the land of the living; Because of the transgression of my people he received the stroke. And he was given a burial place with the wicked, And with the rich in his death, Although he had done no wrong And there was no deception in his mouth. 10 But it was Jehovah’s will to crush him, and he let him become sick. If you will present his life as a guilt offering, He will see his offspring, he will prolong his days, And through him the delight of Jehovah will have success. 11 Because of his anguish, he will see and be satisfied. By means of his knowledge the righteous one, my servant, Will bring a righteous standing to many people, And their errors he will bear. 12 For that reason I will assign him a portion among the many, And he will apportion the spoil with the mighty, Because he poured out his life even to death And was counted among the transgressors; He carried the sin of many people, And he interceded for the transgressors.