1. Joseph translated two sets of plates (see Whatever Happened to the Golden Plates?).
2. Joseph and Oliver specifically identified the location of the final battles of the Nephites and Jaredites (see Letter VII: Oliver Cowdery's Message to the World about the Hill Cumorah).
3. Joseph Smith never once mentioned, wrote about, or endorsed anything having to do with Central America (see The Lost City of Zarahemla and Brought to Light).
4. The Book of Mormon describes North America, with Cumorah in New York (see Moroni's America).
I'll make some more comments about Church history once we release the book titled The Editors. Should be in about two weeks.