No, there is no way currently to infer these are being utilised in a site. An alternative would be to create custom categories, with the proviso that if someone uses a type of "function" you want to track, they have to set the appropriate category in the Site (General) settings (see attachment), and then the API can provide this for your reporting purposes. Obviously this manual process isn't ideal, but it's better than nothing, and can be expanded to include whatever behaviour you want to track.

"categories": {
    "category": [
      {
        "id": "9",
        "name": "Functions - Viz",
        "httplink": null
      },
      {
        "id": "8",
        "name": "Functions - Workflow",
        "httplink": null
      },
      {
        "id": "7",
        "name": "Service",
        "httplink": null
      }