It must be even harder to explain selenehelion, as for me that is the strongest visual proof of a spherical earth.
They claim selenhelion eclipses are proof against a RE, claiming that if Earth was blocking the light of the sun from reaching the moon to cause the eclipse, then you shouldn't be able to see both at once, as that shows there is a path that goes from the sun to the moon without Earth blocking the view.
Of course, for this they ignore that you are above Earth with the horizon slightly below you (especially as this typically occurs from a high mountain), and ignores refraction which also explains why the moon is red during an eclipse, with the light illuminating the moon travelling through Earth's atmosphere and scattering away the blue light.