Reading what @MrMarc said makes sense in that the appellate court feel this should be decided by a jury. The contract the parents have with the lawyer may very well state that they don’t have to pay if the matter goes to court (meaning being heard by a jury); however, if it gets dismissed before going to trial, they would have to pay. This may be why the parents continue to pursue. Also, even though they don’t win, they could still be forced to pay fees (court filing fees, expert witness fees, etc.).
Just curious if the parents will go after the lawyers for legal malpractice if they lose the case. They can always say they were convinced the case had merit and were forced to keep going. Mom is a lawyer, so anything is possible.