For the financial product “SWAP”, we do not offer / allow any manual shift for the repayment flows.
It is indeed correct that the final repayment cannot be edited in the condition details. This is the regular system design as it must be assured that based on the cash flow (incoming/outgoing) the cash flow is balanced correctly to zero after the end-of-term.
There are financial instruments where you have more options to influence the final repayments (such as interest rate instrument, cash flow instrument). However, this is not possible for swaps.
For swaps the final repayment should >always< be after the interest payments. The interest due dates can be shifted/adjusted by some days. In that case the final repayment due must also be adjusted. This logic will not work anymore when users can influence this field. Therefore, we cannot allow a modification of the final repayment for swaps.
If you need to change the due date of the repayment, please consider to change the End date in structure tab.