>>534865976
there's only several who are mentioned, and AW/MW were also vastly trimmed down compared to their beta maps and have very clear signs of having been rewritten when you compare them with each other (such as MW!San Ilia originally having been destroyed and replaced with a giant pit; completely contrary to how it's presented in the final version instead). I don't think they had anywhere near as close a rewrite as the final route, but they did undeniably get changed.
I think there were several beings who were always planned to show up, they just weren't going to be put into a group called "calamities" and be used to pad out the overworld. Koron and Angolmois for example have minor references to them as far back as Part 2. Koron is the only one who is truly developed, however, as Angolmois is quickly and unceremoniously killed off (by Koron). I think there are several of the final calamities who were always going to be around, but the original version was probably going to focus more on the Apostles, as they barely do anything in the final route besides Aprio Lagos.
>>534866417
Xelvy was one of the biggest factors in things being changed and it's because Xelvy was both in charge of a lot of story cutscenes and also in charge of a lot of important story-relevant characters. some of trtr's rewrites are probably him needing to write around something he planned for Xelvy to provide that he never received due to his disappearance.