As Steve Bannon pointed out this morning, Democrats put Trump on trial because they still haven’t gotten over the fact that Hillary lost fair and square. This case has zero to do with a business records dispute.
For the judge and the prosecutor, the case against Trump is that he stole the election from Hillary in 2016. It’s possible that all of the jurors voted for Hillary, so it may be easy to get them to find Trump guilty, no matter how flimsy the legal case is. Merchan and Bragg don’t care if the conviction is overturned on appeal and they get admonished because that may be a year or two after the election.