So what's the deal?
The bonus stays the same (but isn't staggered anymore), the phrasing of the patch notes is just misleading. So archery units get 20% HP Bonus from Feudal and Rattan Archers are not affected by this. Instead they will have 45 HP after this patch.
At least it is like this in the open beta.
Cav-Archers still profit from this bonus, so it's really just wrong in the notes.