Thanks for the reply. The alternative possibilities you suggested tended to be my second guesses.
I might go with the first guesses, because that gives each race 2 units. I suppose the 13th unit is probably best as a human.
Shamans, Hunters, and Zeppelins all do kinda work as either human or elf (Mustard Gas doesn't seem terribly Elf-like, though, so I guess they'll be the Human's third unit).
Either way works, but on second thought, I think the Shaman sounds more Human (with his sarcasm) and the Hunter can be the Elf.
Lizards as the Armour matches the theme of Juggernaut. A good damage unit with a tough hide that is good against all kinds of ground units. (And there isn't really another good spot for Lizards to go.)
Undead for the Devastator and Bomber Balloon makes sense because those are high-explosive weapons designed to pulverize targets - which is important when the targets have no soft flesh vulnerable to nasty shrapnel wounds.
I'm already loving the bits of the Rivellon Times that I've seen. It'll be a delight to read them all in the full game.