Yeah I still have the original world’s. The hard part was trying to figure out which data to keep from each of the worlds. Nobody has been on in some time so I’m not expecting many to come back and can do it on a case by case

Yeah it did a decent job blending new unloaded chunks to ones I pasted in from older worlds. Its still noticeable that something is off but much better than when I tried something similar a long time ago doing a half amplified half regular terrain world.

That time I just followed the ocean on where I could make my breaks roughly down the middle of the map. I forced generated all the right half if the map in amplified, deleted continents that went too far over the center and then switched the world to vanilla terrain and let people explore the non amplified to generate as they go

I added a picture of a piece in this comment https://lemmy.today/comment/25591455

so I think there was some change to the way chunks are generated and it tries to merge the borders properly.
I put all the chunks in empty spots so no two different worlds shared a border, so from what Ive seen the newly created area around is smooth instead of huge cliffs like in the past.
biomes are still a bit weird, like I placed an island from one world that was in the light colored warm water and those parts stick out a bit on the dark colored water of the biome I pasted it into.
I tried to delete as much as I could of the ocean area around land before moving them over

I think this was the mesa that was pasted in but the biome was snow so it sort of merged from amplified to regular terrain and mesa to snow biome. It looks strange but not horrible I guess