I wouldn't think that for each language printed that the plates have to be changed. With the sorting machinery they have, several languages could be printed from one plate because the magazines do have fewer pages.
In languages where there is a minimal run, I would think that they are not using the large presses someone would see on tour. Perhaps there are some smaller presses for these languages with a minimal order.
The Society has already had issues growing accustomed to the advanced presses they use for mass printing. They recognized that it took some time for the press to "warm" up and get the color right, and even changed their schedule in the press room to accomodate the presses. The problem was that they would just start to get the quality they desired and would have to shut the press down for lunch or the end of the day.
Personally, they have such advanced printing presses that they probably are faced with over capacity on their printing needs.