Obie,
I'll try and put a schedule together; but the basic premise is reducing the 10% load to 5% is a 50% reduction in cost. This allows the amounts paid earlier at 10% to cover interest and amortize or curtail the loan. Thus every subsequent payment covers more principal reduction and brings the loan value down.
Obviously, there are some timing issues with an estimate like this but its probably not unreasonable.
My work doesn't even contemplate the fact the borrowings were contrived by the felonious method that FHFA and Treasury cooked the books.
Since all the money was repaid. The money stuffed at FandF when then didn't need it that was repaid, should have drawn no interest. Without studying the 10Q's I wouldn't want to guess, but my sense is nearly all if not all the money should have been without interest or fees because of the government corruption. And if you figure much of the "draws" were circular that would make quite a difference in the outcome.