Let the response
settle the wording.

From the script, with my comments for you.

function pickVariant() {
  // One wording per session, held for thirty minutes in localStorage. That lines
  // up with how GA4 counts a session, so the unit the test is assigned on is the
  // unit it gets analysed on. Change SESSION_MS if you want it per user instead.
  var now = Date.now(), stored = null;
  try { stored = JSON.parse(localStorage.getItem(STORAGE_KEY)); } catch (e) {}
  if (stored && stored.id && (now - stored.t) < SESSION_MS) {
    stored.t = now;
    try { localStorage.setItem(STORAGE_KEY, JSON.stringify(stored)); } catch (e) {}
    for (var i = 0; i < VARIANTS.length; i++) if (VARIANTS[i].id === stored.id) return VARIANTS[i];
  }
  var v = VARIANTS[Math.floor(Math.random() * VARIANTS.length)];
  try { localStorage.setItem(STORAGE_KEY, JSON.stringify({ id: v.id, t: now })); } catch (e) {}
  return v;
}

The label walker. Arrows and icons stay where they are.

function findLabel(btn) {
  // Elementor buttons carry arrows and icons inside them. Walk the text nodes,
  // take the longest one as the label, and wrap only that, so the arrow stays.
  var existing = btn.querySelector('.mi-cta-label');
  if (existing) return existing;
  var walker = document.createTreeWalker(btn, NodeFilter.SHOW_TEXT, null, false);
  var best = null, bestLen = 0, n;
  while ((n = walker.nextNode())) {
    var t = n.textContent;
    if (!t || DECOR.test(t)) continue;
    var len = t.trim().length;
    if (len > bestLen) { bestLen = len; best = n; }
  }
  if (!best || bestLen < 2) return null;
  var span = document.createElement('span');
  span.className = 'mi-cta-label';
  best.parentNode.insertBefore(span, best);
  span.appendChild(best);
  return span;
}

The cloak.

// The reason people say this can't be done on Elementor without a plugin is the
// flash: the original wording shows for a frame before the swap. So the original
// text is made transparent until the new text is in place, and a failsafe lifts
// the cloak after 2.5 seconds no matter what, so nobody ever sees an empty button.
var cloak = document.createElement('style');
cloak.id = 'mi-cta-cloak';
cloak.textContent = INCLUDE.split(',').map(function (s) {
  return s.trim() + ':not([data-cta-rendered])';
}).join(',') + '{color:transparent !important;}';
(document.head || document.documentElement).appendChild(cloak);
function uncloak() { if (cloak.parentNode) cloak.parentNode.removeChild(cloak); }
setTimeout(uncloak, CLOAK_FAILSAFE);

The swap and the four attributes, then the observer.

function applyTo(btn) {
  if (btn.__miDone) return;
  btn.__miDone = true;
  var short = isShort(btn);
  var area  = short ? 'header' : 'body';
  var text  = short ? variant.short : variant.long;
  var label = findLabel(btn);
  if (label) label.textContent = text;
  // These four attributes are the whole contract with analytics. Tag Manager
  // reads them and sends cta_view and cta_click. This script never talks to
  // GA4 itself, so the tracking can change without the script changing.
  if (!btn.getAttribute('data-cta-id')) {
    btn.setAttribute('data-cta-id', location.pathname + '#' + area + '-' + (++autoN));
  }
  btn.setAttribute('data-cta-area', area);
  btn.setAttribute('data-cta-variant', variant.id);
  btn.setAttribute('data-cta-rendered', text);   // set last: this is what lifts the cloak
}

// Elementor renders late and re-renders on interaction, so watch the page for
// its whole life and re-apply to anything new.
new MutationObserver(function () {
  if (pending) return;
  pending = true;
  (window.requestAnimationFrame || setTimeout)(function () { pending = false; sweep(); }, 16);
}).observe(document.documentElement, { childList: true, subtree: true });

The tracking, end to end. Everything the site sends about the test, and where it goes.

# What leaves the page, and where it goes. Nothing here is in the rotator script.

Google Tag Manager
  Variable  DOM element   cta_variant   reads data-cta-variant from the clicked or seen element
  Variable  DOM element   cta_area      reads data-cta-area
  Variable  DOM element   cta_id        reads data-cta-id
  Variable  DOM element   cta_text      reads data-cta-rendered, the wording actually shown
  Trigger   Element visibility   any [data-cta-rendered], once per element, 50% in view   ->  cta_view
  Trigger   Click, all elements  matches a[data-cta-rendered]                              ->  cta_click
  Tag       GA4 event  cta_view   with cta_variant, cta_area, cta_id, cta_text
  Tag       GA4 event  cta_click  with the same four

GA4
  Custom dimensions   cta_variant, cta_area, cta_id, cta_text   registered once, event-scoped
  The read            an exploration: sessions and cta_click by cta_variant, filtered by cta_area
  The number          clicks over views, per variant, per area. The winner is the one that clears it.

Why the attributes and not the script
  The script never calls GA4. If the events change, GTM changes. The script does not.
  If the wordings change, VARIANTS changes. GTM does not.