For once, you're not.
The 2005+ core is, for some reason, lacking a proper title (Likely because it's a handheld-specific core and because the handhelds have had yet to incorporate an AiO executable, this wasn't taken into consideration), so on the core select list it comes up as:
"snes9x2005_plus_libretro.self"
Works fine, though.
Also as an aside, if you exit RA properly (As many SHOULD be doing by now to maintain working configurations), when you return it'll use the last selected core (Out of the box, it runs 2048 for some reason).
Also as another aside, any cores that have an in-game exit option (I.E. PrBoom), it'll exit RA as a whole and not kickback to the top menu.
And the auto-detect core function works. (Only exception being SNES9X 2005+, for reasons above)