The Eastern Church claims it's original, but who knows.
In other words, there's no way to verify whether it's authentic or relates in any way to what Jesus meant.
So, we're back to where we started. Jesus said "generation" and not "tribe" or "people" or "age". We know what "generation" means. He was saying that his prophesy would be fulfilled within the life span of some of the people he was speaking to. Spin it any way you want. That’s what he said and folks have been trying to talk their way out of it for going on 2,000 years.