Honing costs not decreased on Tier 2 gear

I’m looking at the base honing costs for Tier 2 gear and, for example, to go from +8 to +9 (now +10 with the honing buff) it’s 2400 shards. With the total of the buffs it’s supposed to reduce 35% (15% from global and 20% from stronghold) but, instead, it’s only reducing by 18.75%. However, the cost when honing from +8 is 600 shards and, if you take that into account you get the correct reduction of 35% but this is deceptive if it’s intended.

It’s supposed to be that the cost to hone is free now and the “feed” cost is reduced 35%. Instead, it seems like the cost to hone is added to the feed cost and then reduced by 35% and that becomes the new cost to feed. So, we are actually only getting a reduction of 18.75%