Give both teams one example where the request has arrived but loading is unavailable. Ask what each state means in that example, who owns it and what clears it. The ordinary handshake still needs to sit alongside the separately assessed safety functions.
We're listing the lathe supplier's ordinary conditions and the integrator's combination on our own review. The received-but-unavailable example stopped us arguing about which word sounded best. Might help your two teams too.
Owen, yes, provided the combination's meaning is actually agreed. Ravi, I'd also ask what the operator sees while waiting; an accurate internal state can still leave a very confusing prompt.
Keep the recovery question with that work. If an acknowledgement arrives late, the next request mustn't inherit it just because the screen has stopped saying ready.