@wnoblit
As per my knowledge, there is no OOTB feature to correct file names via CSV. You can update metadata for assets via CSV, but not file name.
Changing a file name is like a move operation. File name and references need to be updated to avoid issues.
I would suggest to write your own script and perform this operation in batches or use Renovator (adobe-consulting-services.github.io)
- Please validate all references and asset metadata, after first run. Like live copy references
- If using Dynamic Media, you might have to validare the DM publish/unpublish
- Publish/unpublish of the Asset itself, on live site.
- Publish/unpublish of pages/assets referencing it.
- Consider tuning of asset workflows while renaming. Please validate for any side-effects on turning off the workflows.