The first idea I was just black shoe polish, but I’m not sure if that would really accomplish an acceptable fix. The person who wants me to fix them needs them for a formal occasion, so I would like them to look nice.
Any suggestions?
I agree. If they're not real leather there isn't much that can be done. I mean maybe you could try polishing them and it might hide that, but it'll probably keep flaking.
If they're real leather you could maybe do what OP says, but it will still probably have the rough parts.
Looks like pleather though.