My theme is not translated

by

Make sure you put your function inside after_setup_theme action hook

add_action( 'after_setup_theme', 'load_translation' );

function load_translation() {
    if( is_dir( get_stylesheet_directory() . '/languages' ) ) {
        load_theme_textdomain('adifier', get_stylesheet_directory() . '/languages');
} else {
    load_theme_textdomain('adifier', get_template_directory() . '/languages');
}

Also, you have to make sure your theme domain is matched with the translated file.
For an easier method, I’d recommend you to use Loco Translate, with that plugin you can translate for themes nor plugins directly from wp-admin

Loco Translate Plugin