That is a very good idea! I was thinking we could just get slaves from the Nals (it would save us travelling time) and we could simply specify that the slaves need to know both their language and ours. (Or at least just their original language). Weistgren works as well.
A servant class could be quite interesting! I wonder if we could perhaps have them as slaves that then become servants as they prove their dedication? They could buy their freedom through hard work. They could then live in our village (if we have enough of a foreign population, we could build them their own area; otherwise, we could just get them a house) and live as a translator/ambassador. My problem with letting them buy their way to freedom (and telling them that they are free to go) is that we would then be left without translators. Imagine suddenly losing our only reliable way to communicate with one of our allies.
If that were the case, we would have to purchase another slave/servant or keep three to six of each race on hand at all times. If we let them be free (semi-citizens / ambassadors / "servants" - whatever we decide on) but require that they live in our city, then we only need one or two of each species.
What is done under compulsion is done without understanding. There is no more beauty in it than if one should whip and spur a dancer. -Xenophon (paraphrase). Follow your heart.
Wy'shira = Eloh.