T&Cs now posted on https://www.iberia.com/es/offer/iberia-plus/avios/

Just had a look for MAD-NRT....
no J left (duh) so no DPs
Ws available but not discounted ("The offer will be valid for the purchase of flights (one way or round trip) on the routes offered by Iberia and in the cabins selected for those routes")
Ys are 25% off.
22300*2 = 44600avios (+T&FS) still pretty good for direct flight over with the free XL seats

#brokenrecord get the santander plan for 50%...