Please keep in mind that the articles are aimed at an international, global readership. When translated, I`d suppose that American names, sound "ethnic" or foreign to e.g. a Japanese or Scandinavian reader...
When a general article in the Watchtower e.g. are using names, experiences or quoted from a specific country, the article is most likely written or compiled in that country. E.g. in this issue, the first article is likely written in Poland.
The last article is a life story from Spain, and the name of the author is also given (or as told by)... That life story comes from Spain...