Deepending on how far you got to go you should just accept their demands and get the -2 RR that comes with it. This will give you a modifier for 10 years that will make you unable to modernize your military, but if you westernized as soon as possible, even from oriental(eastern european) tech, you still have at least 33 years worth of waiting to get your centralization slider to -5 to modernize(not counting lucky events). More if you're coming from Moslim or lower tech. Theres no reason to fight them in the mean time, it doesn't stop further westernization and it gives you -2 RR till you're ready to modernize.