A lawyer can mea culpa if they didn’t check and blame ignorance/technology. The judge is saying explicitly that you are on the hook for everything the AI writes.
And more than that (IANAL) the attorney is on the hook not just for a bad filing with questionable info, but explicitly lying to the court about the source of their filings. That is probably an offense that could lead to more punitive actions including disbarment.
Can’t the lawyer still say “I checked to the best of my ability, the best of my ability just wasn’t very good,” or something along those lines?