Well, here's what I'll do.
I'm going to try and fuss with the existing build for a bit, and if I can't fix it, I will get a larger SD card (not enough room on 8gb anyway) and use that for a fresh install of retropie from your supported builds. I assume that Retropie doesn't care how many gigs of storage I give it, does it? There's not like a 32 bit / 64 bit -style limitation on how big the SD card can be, is there?
At which point, i will probably be back asking a million and a half questions about how to set that up!
Thanks.
EDIT: I dunno if this helps anyone, but I've discovered that this problem is isolated to only Retroarch itself and it's Liberato-based emulators. Non-liberatro based emulators work fine, but the retroarch config or any lr- emulators crash on startup with no error message.