Language filter on search form does not contribute to filtered results.

Hello Lcaraves,
Please follow these steps for fine working of multilingual configuration.

a.> First of all you have to check all checkboxes under the MULTILINGUAL module section
Path:- your-site-name/admin/modules
https://www.drupal.org/files/issues/2018-10-15/1.png

b.> Visit here and add your required language for translation
Path:- your-site-name/admin/config/regional/language
https://www.drupal.org/files/issues/2018-10-15/2.png

{I have select Spanish language.}
Then, save the Configuration.

c.> Now visit here and set your translation access for those fields where you want changes.
Path:- your-site-name/admin/config/regional/content-language
And select almost all checkboxes except file.
https://www.drupal.org/files/issues/2018-10-15/3.png

After checked all boxes you will see, there are number of boxes will be visible. Then must checked all relevant boxes.
And select
https://www.drupal.org/files/issues/2018-10-15/4.png

Then Save Configuration.
d.> Now, Visit your content { your-site-name/admin/content} and translate with edit button, which you want to translate in the other language, and save.
e.> If double post will be visible over places there , Then Don’t worry.
f.> Goto their view setting and in Advance setting click , Querry setting.

https://www.drupal.org/files/issues/2018-10-15/5.png

And select
https://www.drupal.org/files/issues/2018-10-15/6.png

Then Apply.

Now come to filter criteria section and select this
https://www.drupal.org/files/issues/2018-10-15/7.png

Then, select,
https://www.drupal.org/files/issues/2018-10-15/8.png

And Apply.

Now you can visit you multilingual site perfectly.
And one thing you site url will be change with language code like this. e.g.,

i.> Spanish Language => your-site-name/es

@babusaheb.vikas Thanks for the detail instructions. Very helpful.

@lcaraves can you try this and let us know? Thanks.

I can confirm the module doesn't preserve the filter on the current language unlike the core module, which does it.

Hello,

searching to filter search results by language, I had hard time to find the right "TAG" for the search exclude query. I put here my solution to filter the search results by language using search_exclude module:

In a [MY–MODULE].module file:

use Drupal\Core\Database\Query\AlterableInterface;
/**
 * Implements hook_query_TAG_alter(): tag search_$type with $type search_exclude_node_search
 * the TAG part = search_search_exclude_node_search (!!!)
 * 
 *  @return Search results in current language
 */
function [MY–MODULE]_query_search_search_exclude_node_search_alter(AlterableInterface $query) {
  $language = \Drupal::languageManager()->getCurrentLanguage()->getId();
  $query->condition('n.langcode', $language, '=');
}

Once you find the TAG, so simple :-)