This is not true. The atmosphere is not transparent. That's why mountains go blue from a distance, and can be invisible from the same distance on some days.
This is not true. Atmospheric diffraction doesn't explain all the things I mentioned. It can explain micro effects, but not the macro effects regularly observed. As indicated before, the atmosphere is not transparent, so you can't see the next continent. You often can't even see a mountain right in front of you, if it is only tens of kilometers away.
Flat Earthers typically admit that eclipses can't fully be explained, which is honest. Ball-Earth theory endeavours to explain it, but this attempt is demonstrably false, by the phenomenum of selenelions, where both the sun and eclipsed moon can be seen at the same time. In ball-Earth theory, the Earth is supposed to be in the middle of the sun and moon (i.e. 180 degrees between Earth, sun and moon), so ball-Earth theory does explain eclipses, but it explains them in a way that is falsified by the (rare) occurence of selenelions (i.e. clearly not 180 degrees between Earth, sun and moon, yet we still have a lunar eclipse).
My refutation of your comments above demonstrate your words may be an example of the very thing you caution against, however well-intentioned these may have been. So do be careful before laying an accusation.