Timing is everything. The standard of proof in a civil case is lower than in a criminal case. If a criminal RICO is proven with these defendants, all Trump has to do in his civil case is file a motion for summary judgment and cite to the findings in the criminal case. For example, if someone is convicted of criminal assault battery, you can sue in civil court for damages and the finding in the criminal case would entitle you to judgment as a matter of law in the civil case. At least as to liability. You'd still have to prove up your personal damages.
I would have to think that he knows they have the goods on each and every defendant to his Civil Rico action, and it's quite a list.
The case isn't sealed, and normally deposition testimony and documents exchanged between the parties would make it to the public record if and when motions are filed with the court about this or that. For example if there was a motion to compel additional document production it might say "So and so testified that he kept a file of handwritten notes that would have been responsive to the document request but those notes have not been turned over." Then the publicly filed motion would cite to the deposition transcript which would be filed as an exhiibit to the motion. In federal court you have to file the whole transcript, so anyone could pull it off of Pacer the federal court docketing system. I would imagine that Team Trump will do as much of that as possible.