To make riven system work better and don't get all the hate because of disposition nerfs, DE should just either add another 0 to any kuva number gain, or make cap reroll price 500 or smth. Current amounts of kuva people get is just pathetic, you must spend days or even weeks killing your brain cells on survival to make few rerolls, which most likely will change nothing, since your riven won't get any better than "sell it for endo". Overall good rolls are happening very rare, you can actually farm other stuff for platinum with better efficiency and just buy whatever riven you want from the market.
Or they can just leave current rivens untouched. If it requires to run extra server — then f***ing do it, DE, you're making absurd profit from your game and for some reason can't buy additional server to store riven data.