How to add the title with a sequence number to inline entity form?

Question

I have an edit form of a custom entity that is passed to the controller:
$form = $this->entityFormBuilder()->getForm($entity_quote, 'edit');

This custom entity has the reference field to another custom entity quote_design. Widget for this field - Inline entity form - Complex.

I added this code to display the word Design above each inline entity form:

/**
 * Implements hook_inline_entity_form_entity_form_alter().
 */
function entity_quotes_inline_entity_form_entity_form_alter(&$entity_form, FormStateInterface $form_state) {

  $form_bundles = [
    'quote_design',
  ];

 if ($entity_form['#bundle'] == 'quote_design') {
   $entity_form['dummy_design_header_title'] = [
     '#type' => 'html_tag',
     '#tag' => 'h3',
     '#value' => 'Design',
     '#attributes' => [
       'class' => ['dummy'],
     ],
   ];
 }

}

And now I see the word Design above every Inline form:

But I need to display the sequence number of this design next to the word Design:

How to implement it?

---

I tried like this:

$created_designs = $form_state->getFormObject()->getEntity()->get('field_design')->getValue();

foreach ($created_designs as $key => $value) {
  $entity_form['dummy_design_header_title_' . $key] = [
    '#type' => 'html_tag',
    '#weight' => -100,
    '#tag' => 'h3',
    '#value' => 'Design ' . ($key + 1),
    '#attributes' => [
      'class' => ['dummy'],
    ],
  ];
}

But then I get the first problem:

And I get the second problem:

When I get the inline forms in this way:
$form_state->getFormObject()->getEntity()->get('field_design')->getValue();
I get only the saved inline forms, but the new inline forms added with the Add another Design button is not there. I need to display the title with a sequence number for both saved and new ones not yet saved.