Translate regular gettext and underscore functions with Polylang's strings

pllstrings.php

<?php 

add_filter('gettext', function($translation, $text, $domain) {
    if(is_admin()) {
        return $translation;
    }
    if($domain == 'mythemedomain') {
        if(function_exists('icl_register_string')){
            $slug = sanitize_title($text);
            icl_register_string($domain, $slug, $text);
            $newtranslation = icl_t($domain, $slug, $text);

            if($newtranslation != $text) {
                $translation = $newtranslation;
            }
        }
    }
    return $translation;
}, 10, 3);
add_filter('gettext_with_context', function($translation, $text, $context, $domain) {
    if(is_admin()) {
        return $translation;
    }
    if($domain == 'mythemedomain') {
        if(function_exists('icl_register_string')){
            $slug = sanitize_title($text.'_'.$context);
            icl_register_string($domain, $slug, $text);
            $newtranslation = icl_t($domain, $slug, $text);

            if($newtranslation != $text) {
                $translation = $newtranslation;
            }
        }
    }
    return $translation;
}, 10, 4);