Clearly, the damage-add value depends on the growth rate of the style that is being used. Is this working as intended? I always thought damage add buffs should add a flat damage that is scaled only by swing-speed.
You are right, i think the Damage add is added to the base damage which then gets multiplied by the damage modifier. But I think the damage add must be added after style calculation for addition to total damage: TOTAL DAMAGE = BASE DAMAGE + STYLE DAMAGE + (DAMAGE ADD*SWING SPEED * (1-TARGET RESIST))
I had the same or a similar error in my spreadsheet (see signature). I also think this is more correct because of changes in 1.58 regarding damage add variance which was kicked out in that patch.