Example

function unmergeAllCells() {
  let app = SpreadsheetApp;
  let activeSheet = app.getActiveSpreadsheet().getActiveSheet();

  let lastrow = activeSheet.getLastRow();
  let lastCol = activeSheet.getLastColumn();
  
  for (column = 1; column < lastCol; column++){
  let mergerange = activeSheet.getRange(1,column,lastrow).getMergedRanges();
  mergerange.map(cells => cells.breakApart())
  }

}

const LANGUAGE_MAP = {
  "RECORD_MESSAGE": {
    "en": "Record message",
    "es": "Grabar mensaje"
  },
  "RECORD_MESSAGE_TEXT": {
    "en": "1. Click here to record your voice",
    "es": "1. Haga clic aquí para grabar su voz"
  },
  "ATTACH_MESSAGE_TEXT": {
    "en": "2. Click here to attach your message",
    "es": "2. Haga clic aquí para adjuntar su mensaje"
  },
  "ATTACH_MESSAGE": {
        "en": "Attach message",
    "es": "Adjuntar mensaje"
  },
  "I_SENT_YOU_AN_AUDIO_RECORDING": {
    "en": "I sent you an audio recording",
    "es": "Te he enviado un mensaje de audio"
  },
  "CLICK_HERE_TO_LISTEN": {
    "en": "click here to listen",
    "es": "haga clic aquí"
  },
  "TO_MY_VOICE_NOTE": {
    "en": "to my voice note",
    "es": "para escuchar mi nota de voz"
  }

function trsl(key) {
  locale = Session.getActiveUserLocale();
  if (['en', 'es'].includes(locale)) {
  return LANGUAGE_MAP[key][locale]
  }
  else {
    return LANGUAGE_MAP[key]['en']
  }
}

 const descriptionRecord = CardService.newTextParagraph().setText(trsl("RECORD_MESSAGE_TEXT"));