hook_libraries_info() doesn't work
hook_libraries_info(), documented in libraries.api.php, is just a hook that informs the Libraries API module of any existing external library. Its purpose is not loading those libraries when a Drupal page is shown; for that, the module needs to call libraries_load() (defined in libraries.module) when necessary.

libraries_load_files() is the function that actually load in the page the CSS and Javascript files, respectively with drupal_add_css() and drupal_add_js().

  // Load both the JavaScript and the CSS files.
  // The parameters for drupal_add_js() and drupal_add_css() require special
  // handling.
  // @see drupal_process_attached()
  foreach (array('js', 'css') as $type) {
    if (!empty($library['files'][$type])) {
      foreach ($library['files'][$type] as $data =&gt; $options) {
        // If the value is not an array, it's a filename and passed as first
        // (and only) argument.
        if (!is_array($options)) {
          $data = $options;
          $options = array();
        }
        // In some cases, the first parameter ($data) is an array. Arrays can't
        // be passed as keys in PHP, so we have to get $data from the value
        // array.
        if (is_numeric($data)) {
          $data = $options['data'];
          unset($options['data']);
        }
        // Prepend the library path to the file name.
        $data = "$path/$data";
        // Apply the default group if the group isn't explicitly given.
        if (!isset($options['group'])) {
          $options['group'] = ($type == 'js') ? JS_DEFAULT : CSS_DEFAULT;
        }
        call_user_func('drupal_add_' . $type, $data, $options);
        $count++;
      }
    }
  }