Improve user experience with Paragraphs on Drupal 8 - Modify the label of paragraph components - source: http://flocondetoile.fr/blog/improve-user-experience-paragraphs-drupal-8

MYMODULE.module

<?php

/**
 * Implements hook_form_alter().
 */
function MYMODULE_form_alter(&$form, FormStateInterface $form_state, $form_id) {
  $form_object = $form_state->getFormObject();

  // Paragraphs are only set on ContentEntityForm object.
  if (!$form_object instanceof ContentEntityForm) {
    return;
  }

  /** @var \Drupal\Core\Entity\FieldableEntityInterface $entity */
  $entity = $form_object->getEntity();
  // We check that the entity fetched is fieldable.
  if (!$entity instanceof FieldableEntityInterface) {
    return;
  }

  // Check if an entity reference revision field is attached to the entity.
  $field_definitions = $entity->getFieldDefinitions();
  /** @var \Drupal\Core\Field\FieldDefinitionInterface $field_definition */
  foreach ($field_definitions as $field_name => $field_definition) {
    if ($field_definition instanceof FieldConfigInterface && $field_definition->getType() == 'entity_reference_revisions') {
      // Fetch the paragrahs entities referenced.
      $entities_referenced = $entity->{$field_name}->referencedEntities();
      /** @var \Drupal\Core\Entity\FieldableEntityInterface $entity_referenced */
      foreach ($entities_referenced as $key => $entity_referenced) {
        
        $fields = $entity_referenced->getFieldDefinitions();
        $title = '';
        $text = '';
        
        foreach ($fields as $name => $field) {
          if ($field instanceof FieldConfigInterface && $field->getType() == 'string') {
            if (strpos($name, 'title') !== FALSE) {
              $title = $entity_referenced->{$name}->value;
            }
            // Fallback to text string if no title field found.
            elseif (strpos($name, 'text') !== FALSE) {
              $text = $entity_referenced->{$name}->value;
            }
          }
        }
        // Fallback to $text if $title is empty.
        $title = $title ? $title : $text;
        // Override paragraph label only if a title has been found.
        if ($title) {
          $title = (strlen($title) > 50) ? substr($title, 0, 50) . ' (...)' : $title;
          $form[$field_name]['widget'][$key]['top']['paragraph_type_title']['info']['#markup'] = '<strong>' . $title . '</strong>';
        }
      }

    }
  }

}