It sounds like something I remember hearing about, so it doesn't surprise me, but...
I wonder about the motivation on the flip side of the deal, with the sister who is learning the foreign languages in the first place. It seems to be rather popular to learn foreign languages to "help out" other language congregations, which has several nice results:
People think you're reaching out, and you gain some sort of status.
Learning a new language and meeting people from a different culture is certainly more exciting than field service as usual. Especially since non-English speakers in the US (probably similar elsewhere) are much more likely to agree to studies. (Probably because they want to learn English, or be American, or what have you.)
Best of all, because you don't know the language very well, you don't notice disturbing phrasing or subtle propagandistic techniques of the magazines that you would probably have picked up on in your native language.
I know about the last one from personal experience, because in my junior and senior years of high school I subscribed to the Watchtower in French (got the cassettes, too). It helped me learn the language, impressed my family, the congregation, and my teacher, made meetings bearable when I took notes at meetings in French... and put off for a little while admitting to myself that I wasn't so keen on the English-language stuff being presented. Towards the end I started annotating my notes with pointed comments and questions, in French, because I knew my mother wouldn't lean over and happen to see what I was writing.
Somewhere in there I figured out that I didn't believe it was the truth, in any language. It just took a little longer.
-T.
