Fundamentally, the problem with part of FET is that their founder has no legitimate qualifications. He was not a MD, and he was not a PhD either, even though even if he WERE a MD, that would give him no grounds to argue on the shape of the Earth since MDs don't study that subject.
But since he lied on both his qualifications, what is to stop him from lying on every other thing he said? And, having read ENaG, it is pretty clear that either one, he did lie, or two, he was simply an idiot. His experiments were sloppy, the results unreliable in the extreme, and completely irrelevant in terms of proving the world's shape. So... where do you go from there? All you can do is go to proving the Earth round.