I'm guess this topic is all within the context of growth in the US?
When I still attended meetings it was easy to notice that there was a slow but steady stream of direction coming from the org that US publishers could "reach out" by learning a new language. In the context of their growth in the United States there is no question that they wish to capatilize on that section of the population. It's just a guess but i'm sure the same thing is also being pushed in other countries with large populations of immigrants (i.e Great Britian, France).
Of course one thing to remember is that the Watchtower primarily would want to go after Christian immigrants. People who already have affiliation with a christian denomination. They don't do so well in converting masses of people from religions that don't share basic christian ideals and concepts (especially Islam).