I want the old beta generation, but with the modern biomes + caves (when i go underground, it's just the boring spaghetti caves)

You can get most of the vanilla biomes by selecting the Beta Vanilla preset. Current versions of the mod do not support noise caves.

werent they supported in older versions?

I removed them during the update to 1.19 due to further internal vanilla world gen changes. I might re-implement them at some point.

I hope you can add them soon, I really love the modern caves, especially with the beta terrain.

would also love to see this return

I removed them during the update to 1.19 due to further internal vanilla world gen changes. I might re-implement them at some point.

Really hope they return soon, having 1.18's caves with beta's terrain really makes the mod stand out further.