Eclipses do not fit together perfectly, as you should know if you've photographed so many. They don't even always fit exactly the same way, as can be seen in the 'ring of fire' phenomenon with solar eclipses. I assume you're only talking about solar eclipses, since the same size comparisons don't apply to lunar eclipses.
Atmospheric conditions do not explain why you see mountain tops first. The air is more rarified, but the tops of the mountains are many more miles away. Also, the mountain tops appear on the horizon, they do not seem to float in the air (although I have seen that illusion with foggy ground conditions).
The haze explanation will kinda work when it comes to seeing Europe through a telescope. There are workarounds for that as well, like trying mountaintop to mountaintop, or even NYC city skyscraper roof to European mountaintop. If your theory about seeing mountain tops first as you approach because the air is more rarified is true, then viewing through the rarified air of higher elevations should do the trick. We make lasers now that would easily cut through the haze, and even pocket lasers will go through quite a bit of it. Global tight beam communication should be possible on a flat earth. It is definitely not possible (with current technology) to do it on this earth.
The calculation you used to measure your apparent drop in Indonesia wasn't exactly correct for your experiment. The number you have here is the total drop from a perpendicular plane, not the amount of curvature. Because you would have been on land, looking at a downward angle toward the beach the drop wouldn't have been easily apparent. Had you set the plane of your telescope perpendicular to earth, them measured the downward angle you had to use to view the beach, and adjusted for your own elevation, you should be able to verify the distance of that perpendicular drop. You could also do the math to see what downward angle should allow you to view an island 50km away on a flat earth.
Assuming that you believe the sun and moon go around a flat earth, how do you explain that the sun and moon don't appear significantly smaller at the apex of their path, where they should be much farther away than they would be at the horizon? Also, how do you explain that there is no edge? And how do you explain that people can fly to the west coast of America by traveling east from Africa, and vice versa? Or the movement of the stars observed from the poles?
Hello there! How you doing?
Am wondering if you came up with an answer to the last question I asked? Relating to the longest line of sight photograph, covering a distance of 275miles. This is not the first time I have reached this point in the conversation only to never hear from the other person again! Does this mean you've simply had enough talking about this subject? Or perhaps it means you don't have an answer to the question? Either way I would love to know.
Same answer applies as the answer to your issue with seeing the white sandy beach through your telescope. Line of sight depends on MANY more variables than just the curvature of the earth.