They technically spawn but all of the actual terrain features that make a caldera what it is don't spawn, they're just a relatively small hill with snow at the top. In 1.16.5 they would have large foothills and the lake in the middle. I assume this might already be a known issue since the 1.18 terrain generation was a huge overhaul, but I didn't see any open tickets for it so I figured I would report it.

just leaving this here. they def do work, but could use some better blending. this is with multiple biome mods in 1.19.2, terrablender vanilla region weight 17.

just leaving this here. they def do work, but could use some better blending. this is with multiple biome mods in 1.19.2

I'm impressed you found one that nice, actually. Even in the 1.16 era they sometimes looked kind of like that. Occasionally you get lucky but with a bunch of biome mods you might end up better off just disabling Caldera generation...

I do think about this from time to time. Biolith has some newer features which might make better calderas possible again in 1.21. However, the other issue with Mojang's modern biome placement is that kind of adjustment takes a huge amount of experimentation (and then when folks install more biome mods it can just toss all that tuning work right out the window...).

oh yeah... I know... I've been trying my best to run all the biome mods I can cram together for a solid decade now, lol. I'm really hoping for a miracle for compatibility soon. Biolith and lithostitched are both projects I'm keeping a close eye on. With my current pack, I actually get quite a bit of calderas... working on structure mod compat for them atm, but overall I really like them. Having caldera and volcanic islands generating smoothly with worldgen like Apollo's has been a long-time dream.

We can leave this open in case anybody else wants to know more, but there are a few points I would like to correct:

1. Even in 1.16, Calderas did not always generate all of the sub-biomes every time.
2. The entire biome does generate in 1.18.2+; it merely happens less often and you may have to search for it.

There is generally speaking no way to make a biome like Caldera generate like it did in 1.16, aside from replacing all of vanilla's surface generation with something more similar to what vanilla did in 1.16. Biomes have roughly zero control over the landscape in 1.18.2+. We are forcing there to be a caldera but it only generates in entirety when vanilla's biome placement happens to hand us a large enough space to work with.

If the Caldera biome as it generates does not please you, it can be turned off in Terrestria's configuration.

I'm marking this as an enhancement request, but the enhancement requested is unlikely any time soon, since it is basically a request for us to completely rewrite Minecraft's biome placement and surface generation code.