How is it possible for any book to be letter perfect?
If indeed there exists a writing/book that is perfect then the writing itself would be more than what we might expect. We might expect any temporal writing to have the signature of the writer himself as an imperfect redactor of the spoken word of God.
No problems with this concept as long as we understand that we are dealing with a mere mortal that is translating by pen and paper concepts that other mortals are to understand. Anything created is in itself a downgrade from that which is eternal. You cannot copy
what is eternally perfect. That which is temporal cannot duplicate the eternal. On the other hand you can expect the eternal to be made understandable in a temporal setting with all the grammatical errors and flaws of a created being such as a man. It remains an absolute truth that there is only one god. There is no entity alongside of him to compare to. The idea that any man made manuscript is perfect in letter is paramount to saying that the writing of a man could in some way match the creator as a dual entity exisiting alongside of and being on par with God himself. This duality that cannot be justified without compromising the nature of God himself as almighty.
Hear oh Israel! You shall have no other Gods beside me!