I belong to two writers' groups. I often ask my peers to read my efforts, or listen when we meet and read aloud. I listen to my peers' efforts as well. It's an honor to share and be asked to review material.
Recently, one member asked me to read the first section of a novel he's been working on, like, forever. I agreed. I have now reread his material twice. It has some errors -- grammatical, word usage, sentence style, typos. I struggled with the dilemma: Do I correct everything or let the writer's unique voice come through? Do I just fix the obvious typos and incorrect word choce?
The voice is not semi-literate. It's just very different.