/core/langs.json

{
  "langs": {
    "en-US": {
      "short": "en",
      "min_confidence": 0.5,
      "fallbacks": []
    },
    "fr-FR": {
      "short": "fr",
      "min_confidence": 0.5,
      "fallbacks": [
        {
          "words": ["merci"],
          "domain": "leon",
          "skill": "welcome",
          "action": "run"
        }
      ]
    }
  }
}