As it stands, the only way I can do this is with bespoke tooling that expands the CSV export into a framework, then re-compiles that to CSV and applies the changes with a Python tool.
And that feels dirty...
Edit: Since this doesn't seem to be in the current project map, I'm gonna clean up my code and submit it in a blog post here later this week. I'll also publish it on github as a public repository so people can help me out with it and get updates.
Edit2: Here it is!