Check "Translate" option for all custom fields in WPML plugin

auto-set-all-custom-fields-as-translatable-for-wpml.js

// Scroll into Custom Fields settings
document.querySelector(".wpml-custom-fields-settings").scrollIntoView();

// Click on 'Display All' button
jQuery(".wpml-custom-fields-settings .display-all").click();

const set_acf_fields_translatable = setInterval(() => {
  // When 'Display All' button is clicked, the 'display-all' class is removed, therefore check until it doesnt exist
  if (jQuery(".wpml-custom-fields-settings .display-all").length == "0") {
    // Scroll into the 'Save' button
    document
      .querySelector(".wpml-custom-fields-settings input[type='submit']")
      .scrollIntoView();
    // Set all custom fields as 'Translatable'
    jQuery(".wpml-custom-fields-settings .wpml-flex-table-row").each(
      function () {
        // Values for radio buttons
        // 0: Don't translate
        // 1: Copy
        // 2: Translate
        // 3: Copy once

        // Check Translate option for all custom fields
        jQuery(this).find(":radio[value=2]").attr("checked", true);
      }
    );
    // Click on 'Save' button
    jQuery(".wpml-custom-fields-settings input[type='submit']").click();
    // Check if the data is saved, then redirect to back the settings page
    jQuery(".wpml-custom-fields-settings .icl_ajx_response").on(
      "DOMSubtreeModified",
      function () {
        if (jQuery(this).text().includes("Data saved")) {
          if (!window.location.hash) {
            window.location.href = window.location.href;
          } else {
            window.location.reload();
          }
        }
      }
    ),
      clearInterval(set_acf_fields_translatable);
  }
}, 1000);

You can copy&paste into console to run it once, since you will probably need this only once.