Is it possible that the gravity of the moon and sun cause the rotation of the pendulum while the earth, whether flat or globe, remains stationary? I'm not sure that considering all the variables involved it could scientifically prove FE or GE if the earth was stationary, and the pendulum affected by the sun & moon. It's difficult to be certain of what's really going on when dealing with some of the weakest forces in nature on a global scale. It leaves little practicality for the scientific method to be used.
I remember seeing an old video of Paul VI entering possibly some UN building and the news commentator made sure to point out the Foucault pendulum half way up the stairs and what it stood for. Not that it means anything, because rotating globe or not, the Catholic faith remains the same, but it came across as a little suspicious.