JAL is quite vague on this on their website as they also put a disclaimer that the calculation would depend on the route and available fare class during reservation.
To give you a reference, I redeemed an award ticket back in 2016 Oct for a 2017 Apr flight in C between DFW - MNL (return) and paid around U$400 during that time.
Another reference point - same DFW - MNL but one-way in PY 2019 Oct (booked 2019 May) and paid U$250.

Hope this helps/