There is no particular reason that a bench trial would make it more likely to be overturned on an appeal. There are two different roles in trial, there's the finder of of law/referee (which the judge typically occupies) and the finder of fact (most commonly the jury). People have a right to waive a jury and instead as the judge to be both the finder of law and fact. In Florida, at least, both parties have to agree to that. I don't know for certain that this is required in NY, but it's incontrovertible that Trump's legal team asked for the bench trial and that AG James et al. had no problem with that.
Appellate courts typically defer to the lower level courts on findings of fact, since the appellate courts aren't "in the room" so to speak, they typically will focus their rulings on legal rulings by the lower court. They CAN go into the findings of fact, but it takes something like "no reasonable jury/finder of fact could have found this to be true" type stuff.