People do you have any idea how many Regioanl dialects exist within each country, which quirks in the language exist only a few dozend miles appart from region to region.
South America is not a small region there could be a lot of Dialects non of you ever heard because they are usualy not shown.

But beside that who ever directed the Actor could at any time stepped in and said something against it but knowing that heavy use of dialect exist mostly in the english version of FF14, she probably got told she should use it.
And it got approved at the end.