Have you tried identifying exactly what is unreadable about it and telling it to make it more readable?

I had GTP-5.6 write some shader code recently and it wasn't very clear to me. I spent about an hour chatting with the until I understood the concepts and was able to express them back to the AI using math formulas and variables named in a way that made sense to me. The AI then rendered the code using the formula and variables I was familiar with and it was clear to me.