How to customize the text for a file (upload) input

Below code is inspired by https://stackoverflow.com/questions/21842274/cross-browser-custom-stylin...

/**
 * Implements template_preprocess_file_managed_file().
 *
 * Below code snippet replaces the file upload element with a click label that
 * is styled as a button.
 *
 * @see https://stackoverflow.com/questions/21842274/cross-browser-custom-styling-for-file-upload-button
 * @see template_preprocess_file_managed_file().
 */
function MYMODULE_preprocess_file_managed_file(&$variables) {
  // Don't alter hidden file upload input.
  if (isset($variables['element']['upload']['#access']) && $variables['element']['upload']['#access'] === FALSE) {
    return;
  }

  // Create an unique id for the file upload input and label.
  $id = \Drupal\Component\Utility\Html::getUniqueId($variables['element']['upload']['#id'] . '-target');

  // Create a label that is styled like an action button.
  $label = [
    '#type' => 'html_tag',
    '#tag' => 'label',
    '#value' => t('Select a file'),
    '#attributes' => [
      'for' => $id,
      'class' => 'button button-action'
    ],
  ];

  // Make sure the label is first.
  $variables['element'] = ['label' => $label] + $variables['element'];

  // Set the custom ID for file upload input.
  $variables['element']['upload']['#attributes']['id'] = $id;

  // Hide the file upload.
  $variables['element']['upload']['#attributes']['style'] = 'position: fixed; top: -1000px;';
}