aaaand…fixed it (after all that)
Searched “Install Google Libraries” plugin, installed it and it works now.
Can anyone tell me why it wouldn’t work ‘stock’?
(interestingly, i just updated my girlfriend’s blog to 4.3.1 and her Visual Editor vanished also – it was there before).
Ah, for reference I’m hosting it on my own domain http://www.bombculture.com (which looks quite sparse right now as i deleted everything).