Antonyms for the word "more attested" would include phrases such as "less proven," "unverified" or "unsubstantiated." These terms indicate factors that may make a statement or claim less reliable or credible, such as a lack of evidence or conflicting information. Other possible antonyms could include descriptions such as "less established," "not well-supported," or "controversial." When evaluating claims or information, it's important to consider the level of attestation or evidence supporting them, to avoid basing decisions or beliefs on unfounded or unreliable information.