Is criticizing poems and officials considered forbidden backbiting, especially if the criticized person dislikes it, and does this apply to historians and scholars mentioning certain historical figures negatively?

Literary criticism is an art that does not fall under prohibited backbiting so long as it is distanced from the person of the litterateur. And what is mentioned in history books and biographies regarding faults does not constitute prohibited backbiting if it is limited to what its owner openly declared. So, whoever openly commits a sin, it is permissible to mention him only with that sin. As for Ibn Sirin's statement prohibiting insulting Al-Hajjaj, it does not contradict what was previously stated, because preoccupation with insulting is blameworthy, even if mentioning what was openly declared is permissible.