Is one who unintentionally causes part of the ink of one of the words of the Mus'haf to be erased sinful, and is he required to replace the Mus'haf?

What you did was not mockery, but rather an unintentional overwhelming, and by cleaning it, you intended to purify it, so there is nothing against you, Allah willing. And as long as the word is legible, we hope there is no liability on you.