Another notable thing I should have mentioned in the original post, is that this draft includes a scene on “Coruscant”, except it’s called “Ton Muund” instead of Coruscant or even Had Abbadon. It’s described as an enormous city that covers the entire planet. It’s the Imperial capital, and the scene takes place in Darth Vader’s quarters. Instead of the Mordor-esque lava castle, Vader’s quarters are described as efficient, technological and dystopian, like something from 1984.

But then later, there’s a different scene, where Darth Vader is in a castle “of black iron in the midst of a crimson sea” which is closer to the famous castle known from Ralph McQuarrie’s concept art and Rogue One. There are even “gargoyles” (some kind of creatures) that hang around the castle. Presumably this castle is on some other planet, but the location is not mentioned.