I want to generate a floating island DIMENSION in 1.16, so I copied the space profile from 1.12.2 and turn it into json manually for the 1.16 config. I also changed the dimensionWithProfiles to my custom profile in common.toml.

The problem is, there is no landscapeType called space (or at least I guess, cuz it crashed)
Using default in landscapeType just generates normally with custom weights.
I also realized there are 7 properties that doesn't exist in the 1.12.2 version:

{
  "lostcity": {
      "terrainFixUpperMinOffset": -1,
      "terrainFixUpperMaxOffset": 1,
      "terrainFixLowerMaxOffset": -3,
      "terrainFixLowerMinOffset": -4,
      "generateNether": false,
      "parkChance": 0.02,
      "seaLevel": 70
  }
}

I think seaLevel might be waterLevelOffset in the 1.12.2 version, but I can't confirm.

Incase you need my profiles, here is the 1.16 profile and here is the 1.12.2 profile from Sky Factory 4.