curl --request GET \
  --url 'https://{domain}/api/v2/network/reports/conversions-columns?api-key='

{
  "status": "success",
  "code": 200,
  "name": "OK",
  "message": "<string>",
  "info": {
    "columns-list": [
      {
        "key": "<string>",
        "field": "<string>",
        "group": "<string>",
        "groupSort": 123,
        "parent": "<string>",
        "level": 123,
        "items": [
          {
            "default": 123,
            "key": "<string>",
            "field": "<string>",
            "label": "<string>",
            "reportSort": 123,
            "sort": 123,
            "width": "<string>"
          }
        ]
      }
    ]
  }
}