Drupal 9 : Ajax process to display an entity form in a popup

Question

I need help I am new in Drupal 9 Ajax development. I have developed a piece of code but it doesn't work. To sumarise, I want to display an entity form in a popup. The popup is built dynamically with jQuery, I use Ajax to fill the popup and the form is built in an ajax command (the code is : \Drupal::service('entity.form_builder')->getForm($livraison, 'edit');)

The form is well displayed but I think I miss something in ajax developpement because when I submit the form, the entity is not saved. When I look at the javascript console log, I see 3 others command responses plus the command I have created in server side (modifLivraison).

result: Array(4) [ {…}, {…}, {…}, {…} ]
​0: Object { command: "settings", settings: {…}, merge: true }
1: Object { command: "insert", method: "prepend", selector: "head", … }
2: Object { command: "insert", method: "append", selector: "body", … }
3: Object { command: "modifLivraison", modif: "...

I think that the Entity form needs some javascript and that's why these 3 commands have been added. I don't know if my ajax process is correct. Here my code : In the command class:

class ModifLivraisonCommand implements CommandInterface
{ protected livraisonId; ...
  /**
   * Implements Drupal\Core\Ajax\CommandInterface:render().
   */
  public function render()
  {
    ...
      $entitytype_manager = \Drupal::service('entity_type.manager');
      $storage = $entitytype_manager->getStorage('livraison');
      $livraison = $storage->load($this->livraisonId);
      ...
        $livraison_form = \Drupal::service('entity.form_builder')->getForm($livraison, 'edit');
        $livraison_form['#cache']['max-age'] =0;
        $output = \Drupal::service('renderer')->render($livraison_form);
        return [
          'command' => 'modifLivraison',
          'modif' => $output
        ];
      ...

The controller :

public function modifLivraison($livraison) {
  $response = new AjaxResponse();
  $response->addCommand(new ModifLivraisonCommand($livraison));
  return $response;
}

and the javascript in the client side :

create_popup('0,0,0,0')
...
jQuery.ajax('/livraisons/modif-livraison/' + livraison, {
  success: function(result,textStatus, jqXHR) {
    jQuery(".spinner").remove();
    console.log(result);
    var ajax;
    Drupal.AjaxCommands.prototype.settings(ajax,result[0],200)
    jQuery(result[1].selector)[result[1].method](result[1].data);
    jQuery(result[2].selector)[result[2].method](result[2].data);
    ...
    jQuery("#modif_livraison").append(result[3].modif);
    ...
  }
})

I think the error is in the way of ajax calling of the url (jQuery.ajax('/livraisons/modif-livraison/' + livraison ...)

My problem is the entity is not saved when the form is submitted. What's wrong ?