Trial counsel must generally raise and preserve the issues for appeal. Failure to do so can result in waiver.
I suppose I did put it too gently. My specialty until my retirement was as an appellate attorney. If this were a criminal case, he might be able to argue ineffectiveness of counsel. In this civil setting, what Trump can argue is extremely limited and his chances of success extremely low. Even the “ties” between the judge and plaintiff’s counsel, which happens all the time, was easily discoverable with amy due diligence.