This fragment was not missing, I just disliked the translation. This is the key phrase of the whole novel and its rhythm in Russian is very powerful.
Не приведи бог видеть русский бунт, бессмысленный и беспощадный! May God grant we never see again so senseless and pitiless a revolt.
I am quite sure the definite article must be used here, because Pushkin wrote about the Russian revolt in general, as a whole. Besides, "русский" was not translated.
So my suggestion is this: Heaven save us from witnessing the Russian revolt, senseless and merciless!