I don’t think there’s any more liquid in a frozen banana—it just sort of separates from being suspended in the fruit’s cell walls (sort of like a tall vs. collapsed meringue has the same amount of egg whites)—so I don’t think you will have to make any adjustments. Once it’s all blended together, my guess is a ‘fresh banana’ mixture would be identical to a ‘previously frozen banana’ mixture.
Happy CRB-ing. This cake is fab, fab, fab!!!