This is all sorts of wrong. How can you nerf such an integral part of pvp? The only parties running bishops right now are from the clans that are already full and dont even have slots to recruit new players. If you're a new player you will never have a healer, never. All the bishops I know rerolled or are only playing in stacked parties. None of them is using any scrolls from donations. I bought an adena scroll, tested and then put it in my wh for when I play a dd.
You have access to data from all interlude seasons and you're lucky you've got clans that keep playing over and over and players that keep coming back. You know players like Lesley, Sin, Luffy, Rhaegar, Mojo, Seif, Kat, Silence, Thouaz, etc always play in "ideal" partys. It's so simple to just get the values of how much people were making in these parties avg per map in the past seasons, change the formulas to the new ones you want to put in and see how that would turn out.
I'm honestly baffled that you think it's ok to not make any changes. I know I won't stick around if my favourite class is unplayable.