Have some 8.2 module/distro config for form or view displays? Use this to add a region to all your fields. Buyer beware!

fixregion.php

<?php

# Run this with drush scr, silly!

use Drupal\Core\Serialization\Yaml;

foreach (file_scan_directory('.', '/core\.entity_.*display.*\.yml/') as $file) {
  $filepath = realpath($file->uri);
  $yml = Yaml::decode(file_get_contents($filepath));
  if (isset($yml['content'])) {
    foreach ($yml['content'] as &$field) {
      if (!isset($field['region'])) {
        $field['region'] = 'content';
      }
    }
  }
  file_put_contents($filepath, Yaml::encode($yml));
}