Hmm, do you actually need the instruction on whether to lie? It feels like the game is mostly going to be about subtle cues and bluffing, and if you let the players choose whether to lie each time, it'll increase the potential for psychological trickery. I suppose it removes the scope for cues (there's no point agreeing that you'll scratch your nose before lying, when you can just huddle beforehand and arbitrarily whisper "right, I'll lie on this one, whatever it is"), but given how easy and undetectable a cue would be, over only a few rounds, maybe that's no great loss.
Does the interpreter know what the motion is going to be before giving the translation, or do they have to try and guess what it's going to be, on the fly?
The main problem with letting them to decide whether or not to lie is that if both sides decide to tell the truth, it will be obvious because both interpreters will be saying the same thing.
Oh, I assumed the Ambassador was just giving each speech once, that each round of speech-and-motion just had one translator, and the teams took turns. So do two translators both translate the same speech at once? Do they speak at the same time (translating line by line), or does the Ambassador deliver his entire speech in silence, followed by two summaries from the two translators?
Ah, okay, that works. Possibly a little tough on the liar if they're going head-to-head against a convincingly written translation, but I'd guess the easiest way to lie is just to invert the gist of whatever's on the script, to invert the adjectives. And there's presumably some interesting power in knowing what the truth-teller is about to say next.
Looks good, anyway, I look forward to catching this from the background tomorrow.
Sounds fun, though I agree with Kevan, fixed lying does sound a bit against the idea of the game, but I'm not sure how it could be changed. Are there two translators translating it simultaneously?