In everyday speech you generally do not try to be this specific, but if you wanted to (e.g. recounting family history to a doctor or talking about the relationship between your parents and granparents) you could use them to be more specific in a clear way.
I agree that almost every use of farfar should be simply translated as grandmother.
English speaking people do not use these all that often. They say "grandmother" or "grandfather". They specify which side of family these come from only when they really need it for some reason.
In Swedish and Norwegian you always specify because the words for grandparents are inherent specific to whether they are paternal or maternal.