Problem to call Hcaptcha callback function

I come to see you because I have been blocking for a week to send the hcaptcha response to Google.

To put it in context, I'm developing a web automation program in Python with Selenium at website.
The captcha is at the end of the forms and should activate the "Finish your order" button

I manage to retrieve the response to the hcaptcha sent by 2 captcha, then put it in the h-captcha textbox. But impossible to send it.

According to the hcaptcha documentation, the callback function is called in the POST request. I have bein found this function, it is hcaptchaOnLoad:

I also found the index.js file where the hcaptcha function is defined and where hcaptchaOnLoad is called.
// Generate hCaptcha API Script
var CaptchaScript = function CaptchaScript(hl, reCaptchaCompat) {
  // Create global onload callback
  window.hcaptchaOnLoad = function () {
    // Iterate over onload listeners, call each listener
    onLoadListeners = onLoadListeners.filter(function (listener) {
      return false;
I enclose the tests that I was able to do in the Chrome console and Firefox as well as my 2captcha code.