NIKKE is just a mess of a game. bugs/glitches nearly everywhere and badly optimized. manipulating gacha rate on client side isn't out of the question for that shit.Well i don't know if that possible, but in nikke they hack the rates for SSR, they change the SSR rates to R rates.
PNC on the other hand seems like in a much better and polished release state, so highly doubt we can manipulate the gacha on client side.