Okay, thanks! I don’t have the beta installed (yet), so for now I will just stick to the regular iOS 9 target and /Documents/cores folder, but this is good to know if I decide to install the public beta.
This does seem like a more annoying way to get cores into RetroArch, but honestly, I don’t update the cores very often anyway. As long as I find ones that work, I’ll stick with what I have.