Thanks for the confirmation.

I also just found this:

faa9fc5c-2706-47b0-baf5-ffcae54f9cbb-image.png

I'd rather not change it and build my own version.

The paths are specified in the docs - for the es_systems.cfg. For the themes, I think it's in the first post, but the idea is that the themes are copied in the /home/pi/.emulationstation/themes folder (which doesn't exist by default, you'll have to create it).