Hmm, I exported only the feet and toecaps this time, and although I have not the faintest idea what UVLayout was thinking when it garbled the UVs, they were recognizable enough that I could cut and paste them back together the correct way. So I finally have toecaps that match the feet both vertex-position- and UV-wise for the first four rows.

Yay! (I guess.)

That was way more painful than it should be. It's close to bedtime now, so I'll puzzle the pieces back together tomorrow and upload it then.

-- I'm not mad at you, just Westphalian.