hook_inline_entity_form_table_fields_alter()

hook_inline_entity_form_table_fields_alter.module

/**
 * Implements hook_inline_entity_form_table_fields_alter().
 */
function MODULE_inline_entity_form_table_fields_alter(&$fields, $context) {
  if ($context['parent_bundle'] === 'MODULE' &&
    $context['entity_type'] === 'MODULE_text_asset') {

    // Remove Title.
    unset($fields['id']);

    // Change label from "Title" to "Question".
    $fields['title']['label'] = t('Question');

    // Answer.
    $fields['field_qna_answer'] = array(
      'type' => 'callback',
      'render_callback' => '_MODULE_render_textarea',
      'label' => t('Answer'),
      'weight' => 3
    );
    
    // Link.
    $fields['field_slide_link'] = array(
      'type' => 'field',
      'label' => t('Link'),
      'weight' => 3
    );
   
    // Add new fields.
    $fields['field_slide_image'] = array(
      'type' => 'callback',
      'render_callback' => '_MODULE_render_thumbnail',
      'label' => t('Image'),
      'weight' => 2
    );
  }
}

/**
 * Custom callback to truncate text size on a pre-defined size.
 *
 * @param string $entity_type
 *  Entity type being processed.
 * @param object $entity
 *  Entity object.
 *
 * @return string
 *  Truncated text.
 */
function _MODULE_render_textarea($entity_type, $entity) {
  if (isset($entity->field_qna_answer[LANGUAGE_NONE][0]['safe_value'])) {
    $string = $entity->field_qna_answer[LANGUAGE_NONE][0]['safe_value'];

    return strlen($string) > 200 ? text_summary($string, NULL, 200) . ' (...)' :  $string;
  }
}

function _MODULE_render_thumbnail($entity_type, $entity) {
  if (isset($entity->field_slide_image[LANGUAGE_NONE][0]['uri'])) {
    return '<img src="' . image_style_url('thumbnail', $entity->field_slide_image[LANGUAGE_NONE][0]['uri']) .'" />';
  }

  return 'N/A';
}