What has yet to be explained, however, is the incredible coincidence where the sun and moon under RET have a difference in size by over four million times yet appear to be the same size in the sky.
I know the explanation isn't satisfying to you, but modern astronomy definitely has one: there are countless billions of planets orbiting countless billions of stars in countless configurations. Some fraction of those planets will have one or more moons that are approximately the same apparent size as their sun. We happen to be on one of those planets. If modern astronomy espoused that we were the only solar system in the universe, then perhaps a deeper explanation would be required.
Asking for more than that is just asking why the Moon isn't bigger or smaller, or why it orbits where it does, or why the Sun isn't bigger or smaller, etc. Science doesn't have an explanation other than that it could have been otherwise, but it happened the way that it did. The outcome wasn't predetermined. It's really not much different than asking modern astronomers to 'explain' why the Saturn is 1.4 billion km from the Sun. Why that number and not 1.5 billion or 1.6 billion or any other number? There are way more number that
aren't 1.4 billion, so why wasn't it one of those? What the odds?!