To change a boolean value on a Progression/Feat, you have two options: The Config Method or directly calling the API

{
  "FileVersion": 1,
  "Progressions": [
    {
      "UUID": "class-progression-uuid - use this or UUIDs, but not both",
      "UUID": ["first-class-progression-uuid", "second-class-progression-uuid"],
      "Booleans": [
        {
          "Key": "AllowImprovement, IsMulticlass, or CanBeTakenMultipleTimes"
          "Value": true/false
        }
      ]
   }
}

The Compatibility Framework contains an API Endpoint to set Boolean values in Progressions or Feats

Behind the scenes, these all work in the same way, so the same API call can be used for all of them, but for ease of use, I've added multiple endpoints that will call the same logic:

• Api.SetBoolean

Your object will look like this:

MyBoolean = {
  payload = {
    modGuid = "Your Mod's UUID as defined in meta.lsx",
    Target = "The Progression or Feat ID you're aiming for",
    FileType = "either Progression or Feat, defaults to Progression if not included",
    Key = "AllowImprovement, IsMulticlass, or CanBeTakenMultipleTimes",
    Value = True or False
  }
}