But of course a court can't dismiss someone's complaint on the grounds that they're nuts; in order to rule on the substance of this case, a court would have to conduct new hearings to gather all the details about the original hearing in which AI was allegedly used. The purpose of judicial immunity is to push all objections to judicial decisions through the appellate courts, which don't have to re-hear everything before issuing a ruling.
And if an appellate court got involved and somehow found a judge outsourced their judging to an AI, it's hard to imagine them accepting that. A "polite suggestion" that the relevant bar or judicial association look in to something, coming from a federal Circuit Court of Appeals, is neither polite nor a suggestion, and will receive the due gravity of a "polite suggestion" coming from one of the most powerful bodies in the country.
the correct steps are appeals in the merit and disciplinary action against the judge
This is not how the legal system works. You need grounds for the Appeal - such as procedural - AND need to get another court to agree with your grounds AND be willing to have the case heard again. None of these are gimmes, and they all take time and money.
Your other criticisms are valid, such as time, money and there is definitely deference to lower court judges. But the recourse for a judge misunderstanding the law (for AI or any reason) is the appeal process.