It doesn't say anywhere that these accounts were "written down in a book". Never.
.
"Those who follow the Messenger, the unlettered prophet, whom they find
written in what they have of the
Torah and the
Gospel, who enjoins upon them what is right and forbids them what is wrong and makes lawful for them the good things and prohibits for them the evil and relieves them of their burden and the shackles which were upon them. So they who have believed in him, honored him, supported him and followed the light which was sent down with him - it is those who will be the successful."
7:157
So, this translation is wrong in your opinion? It says "written". This is a sahih international translation.
I honestly don't understand what you mean. I am not claiming. Quran claims that, they find Muhammad written in what they have of the Torah and Injil.
But thanks. If what you believe make sense to you, let it be.