Hi! For sure, it is acceptable because the first goal of communication is to exchange with others. It is a similar sound, but not exactly the same, so the meaning of words is not really changed. So, in that case, the impact is not really big. The way you prononce the r will give an impression of accent. I don't know the Russian language, but I've read that the r is prononced with the tip of the tongue. In French, it is prononced with the back of the tongue, in the back of the mouth. The feeling is a little bit like when you gargle your mouth.