You need to create custom controller configuration for each game using START+Left. I'm not sure if they persist for games on the SD Card.Yeah. I noticed my mistake right after I had posted.
Here's a better question. Can I set up custom controller configurations?
And what can I do with the ini file beyond what is already there?
The ini file have some libretro core settings, but it's driven by a read-only file, making it almost useless.