Group by multiple keys in object array javascript

I have a nested array of objects which looks like something like below.

[
    {
        "region": null,
        "country": null,
        "territory": "Worldwide",
        "territoryCode": "ALL",
        "t2": null,
        "t3": null,
        "t4": null,
        "t5": null,
        "t6": null,
        "t7": null,
        "localLanguage": {
            "territoryId": 1,
            "localLanguageName": "N/A",
            "localLanguageCode": null
        }
    },
    {
        "region": "Africa",
        "country": "Madagascar",
        "territory": null,
        "territoryCode": "MG",
        "t2": "AFR",
        "t3": "MG",
        "t4": null,
        "t5": null,
        "t6": null,
        "t7": null,
        "localLanguage": {
            "territoryId": 30,
            "localLanguageName": "Malagasy, French",
            "localLanguageCode": "MLG, FRE"
        }
    },
    {
        "region": "Africa",
        "country": null,
        "territory": null,
        "territoryCode": "AFR",
        "t2": "AFR",
        "t3": null,
        "t4": null,
        "t5": null,
        "t6": null,
        "t7": null,
        "localLanguage": {
            "territoryId": 2,
            "localLanguageName": "N/A",
            "localLanguageCode": null
        }
    },
    {
        "region": "Africa",
        "country": "Morocco (incl. Western Sahara)",
        "territory": null,
        "territoryCode": "MA",
        "t2": "AFR",
        "t3": "MA",
        "t4": null,
        "t5": null,
        "t6": null,
        "t7": null,
        "localLanguage": {
            "territoryId": 35,
            "localLanguageName": "Arabic, French",
            "localLanguageCode": "ARA, FRE"
        }
    },
    {
        "region": "Africa",
        "country": "Morocco (incl. Western Sahara)",
        "territory": "Morocco (excl. Western Sahara)",
        "territoryCode": "MAXEH",
        "t2": "AFR",
        "t3": "MA",
        "t4": "MAXEH",
        "t5": null,
        "t6": null,
        "t7": null,
        "localLanguage": {
            "territoryId": 36,
            "localLanguageName": "Arabic, French",
            "localLanguageCode": "ARA, FRE"
        }
    },
    {
        "region": "Africa",
        "country": "Morocco (incl. Western Sahara)",
        "territory": "Western Sahara",
        "territoryCode": "EH",
        "t2": "AFR",
        "t3": "MA",
        "t4": "EH",
        "t5": null,
        "t6": null,
        "t7": null,
        "localLanguage": {
            "territoryId": 37,
            "localLanguageName": "Arabic, French",
            "localLanguageCode": "ARA, FRE"
        }
    }
]

I'm looking to group my entire data object on the basis of unique region, country, t2-t7 combinations. I'm looking to have an output like this

[{
  "region": "Africa",
  "country": [{
      "desc": "Madagascar",
      "t2": [{
        "id": "AFR",
        "localLanguageName": "Malagasy, French",
        "localLanguageCode": "MLG, FRE"
        "t3": [{
          "id": "MG"
        }]
      }]
    },
    {
      "desc": "Morocco (incl. Western Sahara)",
      "subTerritory": [{
        "t2": "AFR",
        "t3": [{
          "id": "MA",
          "localLanguageName": "Arabic, French",
          "localLanguageCode": "ARA, FRE"
          "t4": [{
              "id": "MAXEH",
              "localLanguageName": "Arabic, French",
              "localLanguageCode": "ARA, FRE"
              "t5": [{
                "id": ""
                  .
                  .
                  .
              }]
            },
            {
              "id": "EH",
              "localLanguageName": "Arabic, French",
              "localLanguageCode": "ARA, FRE"
              "t5": [{
                "id": ""
                  .
                  .
                  .
              }]
            }]
        }]
      }]
    }]
}]

I'm looking at the most efficient way to group the data. Is it better to use a hashmap ? or the map/reduce methods in Javascript ?

I have tried the below. It's a lot incomplete, but I'm stuck after a couple of iterations.

    const result = Object.values(data.reduce((key, curr) => {
        const { region, country, t2, t3, t4, t5, t6, t7 } = curr;
        if (!key[country]) {
            let obj = {};
            obj.region = region;
            obj.country = country;
            obj.t2 = [{
                id: t2,
                t3: [{
                    id: t3,
                    t4: {
                        id: t4,
                        t5: t5
                    }
                }]
            }];
            key[country] = obj;
        } else {
            key[country].t2 = key[country].t2 || [];
            const foundCountry = key[country].t2.find(x => x.desc === t2);
            if (!foundCountry) {
                key[country].t2.push({
                    id: t2,
                    t3: [{
                        id: t3,
                        t4: {
                            id: t4,
                            t5: t5
                        }
                    }]
                });
            } else {
                const tx = foundCountry.find(x => x.id === t3);
                if (!tx) {
                    foundCountry.push({
                        id: t3,
                        t4: {
                            id: t4,
                            t5: t5
                        }
                    });
                } else {
                    tx.id = t3;
                    tx.t4 = t4;
                }
            }
        }
        return key;
    }, {}));
    console.log(util.inspect(result, false, null, true))
    return result;

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