Version 31~32 resource pack doesn't create custom language

{
    "pack": {
        "pack_format": 15,
        "supported_formats": [15, 40],
        "description": "Changes Language"
    },
    "language": {
        "cus_tom": {
            "name": "Custom Lang",
            "region": "Custom Region",
            "bidirectional": "false"
        }
    }
}