A Chicago law firm’s quest for a $9.75 million “fee enhancement” in a high-stakes divorce case made a return trip to the Illinois Appellate Court.A Cook County judge ruled that the bonus provision in a retainer agreement — which said the client agreed to pay a final bill that included hourly fees and an extra amount set by the firm based on the factors that the Rules of Professional Conduct provide for ascertaining the reasonableness of a fee — was too indefinite to be enforced.Richard Stephenson reportedly paid $3.75 …