As you have explained, Enoch I, II and III are completely different types of manuscripts - Ethiopic, Slavic and Hebrew. The content is very much different.
The E.Isaac translation of I Enoch in Charlesworth's "Pseudepigrapha" uses as a primary text "the fifteenth-century Ethiopic manuscript found in a monastery in Kebran, in Lake Tana." He continually compared that manuscript with a late eighteenth century one found in the Garrett collection at Princeton University and with the text of R.H. Charles. He followed the latter two when the primary text was obviously wrong or unintelligible. He also compared the primary text with existing Greek fragments (Akhmim, Syncellus, Greek papyrus as edited by Bonner.) The Qumran fragments were also consulted.
The commentary and footnotes explain the differences between the manuscripts, context, relationship to Scripture, etc.
Previously on this forum I have bothered to type in large segments of the Isaac translation to compare to the Laurence translation which is readily available on the web so that posters can see the difference. It takes a lot of time and I'd rather not have to do it again to make my point.
As I recall, one occasion was a crevo debate when the correspondent demanded modern day evidence supporting fulfilled prophecy.
To make a long story short, scholars proceed under the presumption that prophecy is impossible. Thus the older web translation (I believe it was Laurence's) included a footnote remarking a certain passage was clearly referring to Herod and that therefore I Enoch had to have been written after he lived.
Of course that translation was before fragments of a copy of Enoch were discovered in the Dead Sea Scrolls. Some of the astronomy related fragments were carbon dated (as I recall) to around 200 BC.
The exclusion of the book from canon makes sense, though, due to authorship that is apparently varied (even though there are canonical books with this quality as well), and, pertaining to the Antediluvian era, before the Mosaic Law as it was, its inclusion would not necessarily lend to the theological consistency and clarity that early Christians, and eventually the Catholic church, sought in assembling their Biblios, our Bible, that I accept as divinely guided and inspired. The New Testament actually is foreshadowed and essentially foretold by this book, 1 Enoch, imho.
What are your thoughts?
And, if you have any notion of when that crevo thread that you mention occurred, it's title, subject, etc. so I can do a search and read it myself, that would be much appreciated. It must be pre-2005, because I've read nearly all of them, and participated in many, since then.