I did quick search via google and the recent and one before it message index to see if this had been discussed and didn't find it.
I came across the essay linked below when researching Japanese gardens in the US. A little aside on page two of the essay says that this Japanese family introduced the fortune cookie as part of the Japanese tea garden created in a park as a result of the Japanese Village for the 1894 World's Fair. It mentions that the idea was picked up by entreprenuerial Chinese who, as we all know, made it the norm in most US Chinese restaurants.
The essay/memoir is a little imprecise. For example, while possible, I find it unlikely that the same superintendent for parks after the 1894 World's Fair would also be in position of responsibility after WWII. It may just be the way that the essay is written that creates that impression.
Anyway, wondering what you knowledgeable might think/know about this.