currently BC books FX revaluation on bank accounts to realized FX, and FX revaluations on AP and AR to unrealized FX.

This isnt right.

Realized FX should be calculated when it is realized.

So for example revaluation of foreign exchange on cash held in bank in a foreign currency should be booked to unrealized FX, it will only be realized when this cash is either paid out of the company, or when the cash is converted to local currency.