locale_storage.php

<?php
/**
 * Submit handler to save config translation.
 */
function config_translation_form_submit(&$form, &$form_state) {
  $form_values = $form_state['values'];
  $language = $form_values['language'];
  $group = $form_values['group'];

  // For the form submission handling, use the override free context.
  config_context_enter('config.context.free');
  // $existing_translation_objects = locale_storage()->getTranslations(array('language' => $language->langcode, 'translated' => TRUE));
  foreach ($group->getNames() as $id => $name) {
      // Set config values based on form submission and original values.
    $base_config = config($name);
    $translation_config = config('locale.config.' . $language->langcode . '.' . $name);
    config_translation_set_config($base_config, $translation_config, $form_values[$id]);

    // If no overrides, delete language specific config file.
    $saved_config = $translation_config->get();
    if (empty($saved_config)) {
      $translation_config->delete();
    }
    else {
      $translation_config->save();
      $locations = locale_storage()->getLocations(array('type' => 'configuration', 'name' => $name));
      if (!empty($locations)) {
        // This was a shipped config file so save translations with locale DB too.
        $target = locale_storage()->createTranslation(array('lid' => $locations->lid, 'language' => $language->langcode));print_r($target);exit;
        $target->save($saved_config);
      }
    }
  }

  config_context_leave();

  drupal_set_message(t('Updated @language configuration translations successfully.', array('@language' => $language->name)));
  $form_state['redirect'] = $group->getBasePath() . '/translate';
}