The money went directly to the college. Wouldn't the court have to order the college to return the money? And does that ever happen?Making a bona fide loan with an interest charge is not a fraudulent transfer. It would be a fraudulent transfer if you made the loan and never intended to enforce it or planned to simply forgive the loan later, i.e. the loan was really a disguised gift. Since the son indeed repaid the loan with interest there is clearly no fraudulent transfer here and the creditor should not succeed in any effort it makes to pursue your son for it.
That payment of tuition and fees, on the other hand, would be potentially fraudulent transfer because you in effect made a gift to your son of the $15,000. It is no different than had you given Jim the cash and Jim paid the tuition and fees himself. You made the transfer and got nothing back of equivalent value in return at a time that you were insolvent, which is the basic description of a fraudulent transfer. So the creditor might well succeed in getting a court to order your son to return the $15,000 to you so it can take that money to satisfy the judgment against you. Whether it will succeed depends on exactly what is presented to the court, so there's no way for me to predict the outcome of that.