I can’t exactly remember but he added a couple of letters to the Rs. Many people translate it as just that, as if Denisov had rhotacism. I think he was actually trying to depict a French glottal R.
That’s what I think. At the time in Russia it was in vogue to know French. One guy even goes by Pierre instead of Pyotr. It’s a pretentious high-brow thing, not a speech impediment.
Maybe somebody on lit.se will know if Tolstoy ever talked about his intent there.
I started and stopped it in disgust three times before I could make it through. I read it along with a friend and we helped each other through. He was thoroughly exhilarated by it.