The multilingual chat program in Google Sheets internally uses the Language App service to perform the translation. When a user enters any text, the onEdit() method is triggered which performs the translation and updates the sheet.

You can also use the GoogleTranslate() formula to perform inline language translations without using Google Apps Script. And you can perform translation in all languages that are supported by Google Translate.

function onEdit(e) {
  try {
    var cell = e.range.getA1Notation();

    if (e.value && (cell === "A6" || cell === "E6")) {
      var sheet = e.source.getActiveSheet();
      var data = sheet.getRange("C4:G5").getValues();

      var langA = getLanguage(data[1][0]);
      var langB = getLanguage(data[1][4]);

      if (langA === "" || langB === "") {
        Browser.msgBox("Please select the languages of participants from the dropdowns in cell C5 and G5");
        return;
      }

      if (langA === langB) {
        Browser.msgBox("Please select a different language for each chat participant");
        return;
      }

      var userA = data[0][0];
      var userB = data[0][4];

      var colA, colB;

      if (cell === "A6") {
        colA = userA + ": " + e.value;
        colB = userA + ": " + LanguageApp.translate(e.value, langA, langB);
      } else {
        colA = userB + ": " + LanguageApp.translate(e.value, langB, langA);
        colB = userB + ": " + e.value;
      }

      sheet.appendRow([colA, "", "", "", colB]);

      e.range.clearContent();
    }
  } catch (error) {
    Browser.msg(error.toString());
  }
}

Google Translate Languages

This is a list of languages and their ISO languages Codes that are currently supported by Google Translate. When sending the translation request to the Language Translation API, as in the case of translating RSS Feeds, always make sure that the two language codes are different.