I know several dialects that are dying out, that lived and evolved for hundreds of years within 50km of each other, each of which is practically incomprehensibl

I know several dialects that are dying out, that lived and evolved for hundreds of years within 50km of each other, each of which is practically incomprehensible to a speaker of the other. Seeing them in written form is painful, because some kind of mapping has to be invented to the latin character set, and I can absolutely see someone inventing their own characters for the sounds not represented.