If it is indeed the case that everyone knows for certain what the signals mean, then they can be very specific communications of intent and consent: there is not actually any guessing going on!

It's possible to send signal A and the other person not understanding what the signal means and doing nothing.

But it's also possible that they don't understand the signal but the signal causes them to feel a certain emotion and that emotion lets them engage in an action without them having any idea of the casual chain.

The more I learn about how humans work the more I get those practical ethical dilemmas. Even worse, to really know what I'm doing I have to experiment and I'm curious ;)