can someone help me understand why we need to do this? from borrowed amount and current amount perspective
I’m not sure I understand the question.
In a currency swap (as defined in the CFA curriculum), the notional principals are exchanged at the initiation of the swap, and at the termination of the swap.
yes, in that case why would that be necessary?
It’s not necessary.
Remember, swaps are custom derivatives; the parties can set them up any way they want.
CFA Institute simply assumes that the principals are swapped at the beginning and at the end.