I mostly agree with you here. I definitely think that Japanese holidays should have their place (my May, July, and September ideas are based on Japanese holidays) along with western holidays, but I think the best way to go about it is to use Japanese and western holidays as bases and then add a healthy spattering of "Eorzean" theme to it.
I did think of White Day for March, but I was trying to avoid holidays that only existed in one culture or the other. ;)
