That's what they say about Christians, who stole their scriptures. I'd be scandalized too. Look what the Mormons did with Christianity and now they pretend to be "Christians."
Again, hardly informative or convincing.
Also, what makes you think that they understand the meaning and purpose of the OT Scriptures any better than, for example, Caiaphas did 2000 years ago? And in this, let us remember, it has nothing to do with the understanding of the Hebrew language. That is a given in both cases. Given what the OT prophets say repeatedly, the problem was not restricted either to those of 21st century or the 1st century A.D.