Hi No Name - it the DOJ or the Comptroller General which would have oversight for UST actions? If it was actions of individuals - then probably the FBI would get involved and you would be right because the FBI is part of the DOJ. In this case it has to do with a accounting decision by the UST itself and would fall under the oversight of the Comptroller General?
Why not just let the $187B ride, and collect the 10% on that? Is the conversion even necessary? By the time they are released, GSEs may be able to send the first $19B to Treasury and slowly redeem the LP after Treasury's commitment is ended. Assuming the contracts aren't modified to allow for a paydown mechanism or adjustment sooner.