Rasec, is this the complete question? I think you’re missing currency-related information… are rates rising/falling. You’ve a lot of “if’s” in your bullets, but does the question who the parent/sub is and their related functional/presentation currencies?
I think your exchange rates are mixed up. Think of this in terms of expenses. USD is depreciating and SGD is appreciating.
Current Method: You use the average (0.662) rate to go from SGD to USD, meaning you’re recording a higher COGS in terms of SGD.
Temporal Method: If you use the temporal method, inventory is marked at the historical (0.654) rate since it’s a nonmonetary asset. Since few months ago, SGD was lower, your COGS would be lower.
Revenues are recorded at average rate under both methods. So when you net things, temporal method gives your a higher GP.