Curious as to what precisely makes Full-Preterism considered an non orthodox heresy?

[Ed Parenteau]

That view denies the future Second Coming of Jesus and the Physical resurrection that would happen at that time, so historical has been seen as heretical view

So who cares about the false views of history? It denies what Christ clearly said right along with this dire warning: Rev22:18I warn everyone who hears the words of the prophecy of this book: if anyone adds to them, God will add to him the plagues described in this book, 19and if anyone takes away from the words of the book of this prophecy, God will take away his share in the tree of life and in the holy city, which are described in this book. .

Here are Christ's very last words and all stated in the present tense: So, do what "tradition" has taught you and change them to your hearts delight and make them mean "I am not coming soon". Do you believe Jesus or the creedal traditions? Did Jesus mean what He said or the opposite of what He said?
Revelation 22:7“Behold, I am coming soon. Blessed is the one who keeps the words of prophecy in this book.”...12“Behold, I am coming soon, and My reward is with Me, to give to each one according to what he has done. 13I am the Alpha and the Omega, the First and the Last, the Beginning and the End....” 20He who testifies to these things says, “Yes, I am coming soon.” Amen. Come, Lord Jesus!

It all fits perfectly with Jesus's emphatic promise:
Matthew 24:Truly, I say to you, this generation will not pass away until all these things take place.