The current working values for prestige and piety look very low for a 'wonder'. There could probably be a pass on prestige and piety bonuses in general, but here's a few notes from what's in the game at the moment
Nice write up; I'm not a content designer but I will show it to them
I do think that it might be the case that the modifiers and their values were just added to show off how we display modifiers though.
Remember that a lot of things (especially values) in the images are WIP.