Okay, he got back fast and says the erratic movements look like a problem with the nervous system and that Harry also looks impacted but that given the erratic movements, it's far more likely something is wrong with Harry's nervous system. He also said, "Poor fella".
Sorry that the second opinion was no good either but since it was free, I figured it'd be worth it to get one for you. From your overall care, I don't think there were too many mistakes, if any, in your husbandry. Some axolotls simply just get these problems.