If company A swaps their debt with Company B (Company B is the debtor, so it is a Company A asset) and in the exchange they take a longer dated note with a smaller coupon, would Company A book a loss on the swap or leave the note at its face value?
What you are describing sounds not as a swap of debt but as a refinancing of B's debt with A. If so , then A has to recalc the PV of the what B owed to it before the refi and after. If A is getting a worse deal then its a loss to A. Can't tell right off because the term went longer although the rate went down so you have to do the math. Look up "troubled debt restructurings" for detailed acctg guidance.