As
Popper noted, science often proceeds by disconfirmation or falsification, rather than by proof or verification. So, create a model of reality, say, the world we live on is a nearly flat plane, and see whether the observations match up.
Regarding the FE model, it soon became apparent, indeed more than two thousand years ago, that it was very difficult to model reality using the FE assumptions. You have to explain stuff like sunset and sunrise, longitude, the pole star etc etc.
The modern FE movement tries to deny this science, however it is incumbent upon them to show how the standard and well-known problems can be explained under the FE model. E.g. why is half the world in darkness at any one time? That’s really hard.