As far as I know here, the mesh gets manually triangulated by our export script before exporting. Since it's done by script it's reversible/non destructive: create a copy of the mesh, triangulate, export, delete the copy.
I am bumping this for more people to read. This is still a huge pain in the ass for me. Is there anyone here who knows melscript who could say if it was possible to match maya's internal triangulation to what is going on in the viewport? Or if there is any way to write a custom triangulation script that can force…