OP lost me when he said the edges of his Mac were “painfully sharp”…
Why? I agree. I could send you pictures of indentations in my skin, right below my wrists, that are present on my arms right now. It's a bit better with the newest, thinner, generation, but last generation was uncomfortable enough that I would use wrist support, or drape a mousepad on the edge. An 8 hours shift of typing would get uncomfortable, with questions of "wtf happened to your wrists?". Not to mention the ever present indentation in my hand, like this [1]. I'm probably "holding it wrong".
[1] https://www.reddit.com/r/mac/comments/1k07yqj/sharp_edges/
Then make it valid UTF-8. If you try to solve the long tail of issues in a commonly used function of the library its going to cause a lot of pain. This approach is better. If someone has a weird problem like file names with invalid characters, they can solve it themselves, even publish a package. Why complicate 100% of uses for solving 0.01% of issues?
I think you misunderstand. How do you do that for a file that exists on disk that's trying to be read? Rename it for them? They may not like that.