I have never watched those, but, using FMA, didn't the author have a purpose for the Ishbalan? Yes, there was a very good reason the Author used them. And I am guessing you can look at the other Anime and see there was a reason they used another ethnicity. So if you look at why the Author chose to make Chad Hispanic one of the major reasons he was showing Catholocism (My point).
Thank you. I have a whole post on this on COPS if you care to continue to disbelieve I am right. ^_^