I realize you do not see a paradox here - and I have found one scholar (Chris King) who also dismisses it with a Hellenistic hand wave. But the other scholars I've read are not so easily convinced.
Here are some of my "digs" (I found the first two sections online in several places and didn't select for the 'best' source.)
The third Enochian book, the Book of Astronomy, is considered the oldest of those preserved, thought to have been written well before the second century. It contains a description of the structure of the universe as well as the details of a 364 day solar calendar, a calendar that seems to have been popular especially in the Dead Sea Scrolls although it is well supported by another pseudepigraphic book, Jubilees.
"Chaps. 72-82 The Astronomical Book, like the Book of Watchers, may date from the third century BCE; the oldest copy of it seems to have been made not long after 200 BCE. Sizable portions of the text are preserved on four copies, written in Aramaic, from Qumran cave 4. The Aramaic original appears to have been much different and much longer than the Ethiopic text, adding far more astronomical details." - James C. Vanderkam
1 Enoch is an unmistakable product of Hellenistic civilization. A world view so encyclopaediac that it embraced the geography of heaven and earth, astronomy, meteorology, medicine was no part of Jewish tradition - but was familiar to educated Greeks, but attempting to emulate and surpass Greek wisdom, by having an integrating divine plan for destiny, elaborated through an angelic host with which Enoch is in communication through his mystical travels. - Chris King.
"One of the most remarkable features of 1 Enoch is that the law revealed to Moses on Mt. Sinai plays almost no part in it at all. It could be objected that it would be more surprising if it did have a role, since 1 Enoch is, of course, about Enoch who lived before the flood (see Gen 5:21-24) and thus long before the law was revealed. The argument would be that the authors of 1 Enoch were consistent about their pseudepigraphic attribution of the material to Enoch and therefore did not commit the anachronism of having him teach and obey the law of Moses.
"But there is a flaw in that argument because at least two places in the book should mention the law revealed on Mt. Sinai. The two places are in the two principal apocalypses, the Apocalypse of Weeks and the Animal Apocalypse. Both of these revelations cover the period when Israel was in the wilderness and, according to the pentateuch, received the covenantal law." - James C. Vanderkam
The Old Testament Pseudepigrapha volume I - Charlesworth
“Some scholars believe that the original language of 1 Enoch is Hebrew; others, however, think it is Aramaic; still others contend that the book, like Daniel, was composed partly in Hebrew and partly in Aramaic.”
“We are not certain about the city or place in which 1 Enoch was, or its constituent parts were, composed. However, it is clear that the work originated in Judea and was in use at Qumran before the beginning of the Christian period.”
93.2 And Enoch said: "Concerning the sons of righteousness, and concerning the chosen of the world, and concerning the plant of righteousness and uprightness, I will speak these things to you, and make them known to you, my children. I, Enoch, according to that which appeared to me in the Heavenly vision, and that which I know from the words of the Holy Angels, and understanding from the Tablets of Heaven."
93.3 And Enoch then began to speak from the books, and said: "I was born the seventh, in the first week, while justice and righteousness still lasted.
93.4 And, after me, in the second week, great injustice will arise, and deceit will have sprung up. And in it there will be the First End, and in it, a man will be saved. And after it has ended, iniquity will grow, and He will make a law for the sinners.
93.5 And after this in the third week, at its end, a man will be chosen as the Plant of Righteous Judgment, and after him will come the Plant of Righteousness, forever.
93.6 And after this, in the fourth week, at its end, visions of the righteous and Holy will be seen, and a Law for All Generations, and an enclosure will be made for them.
93.7 And after this, in the fifth week, at its end, a House of Glory and Sovereignty will be built forever.
93.8 And after this, in the sixth week, all those who live in it will be blinded. And the hearts of them all, lacking wisdom, will sink into impiety. And in it, a man will ascend, and at its end the House of Sovereignty will be burnt with fire. And in it the whole race of the chosen root will be scattered.
93.9 And after this, in the seventh week, an apostate generation will arise. And many will be its deeds - but all its deeds will be apostasy.
93.10 And at its end, the Chosen Righteous, from the Eternal Plant of Righteousness, will be chosen, to whom will be given sevenfold teaching, concerning his whole creation.