Multi Language (Menu not showing)

Site URL: https://www.gregorykoefer.com/de/home

Hey guys,

I've followed the tutorial of https://www.bradgood.net/articles/multi-language-content-on-any-squarespace-template 

and replaced everything of /es/ with my own slugs (en)

It seems to work except, that when I visit the german website, the menu isn't showing. IN the backend everytime I click on the de/home site, the menu loads quickly and dissapears immediately.. 

Here is my current code I've injected in the footer: 

<link rel="stylesheet" type="text/css" href="https://cdnjs.cloudflare.com/ajax/libs/flag-icon-css/2.6.0/css/flag-icon.css">
<script src="https://ajax.googleapis.com/ajax/libs/jquery/3.4.1/jquery.min.js"></script>
<script>
    $(function() {
    /* SETUP MULTI-LANGUAGE */
    var defaultLanguage = 'en';
    var lang = location.pathname.split("/")[1];
    var defaultClass = 'lang-'+defaultLanguage+'';
    var itemParent = "nav [class*='collection'],nav [class*='folder'],nav [class*='index'],nav [class*='group']";
    if (lang == "" || lang.length > 2 ){
      var lang = defaultLanguage;
    }

    /* ADD LANGUAGE CLASSES */
    $('a[href="/"]').addClass('lang-'+defaultLanguage+'').parents(itemParent).addClass('lang-'+defaultLanguage+'');
    $('nav a:link:not([href^="http://"]):not([href^="https://"])').each(function () {
      var langType = $(this).attr('href').split("/")[1];
      var multiLanguageClass = 'multilanguage lang-' + langType + '';
      if (undefined !== langType && langType.length <= 2) 
        $(this).addClass(multiLanguageClass).parents(itemParent).addClass(multiLanguageClass);
    });
    $('nav button').each(function () {
      var langTypeFolder = $(this).attr('data-controller-folder-toggle').split("/")[0];
      var multiLanguageClass = 'multilanguage lang-' + langTypeFolder + '';
      if (undefined !== langTypeFolder && langTypeFolder.length <= 2) 
        $(this).addClass(multiLanguageClass);
    });

    /* HOMEPAGE-LOGO LINKS TO PROPER LANGUAGE HOMEPAGE */
    if (lang == "de") {
      $('a[href="/"]').attr("href", "/de/main/");
    }

    /* ADD EXCLUSION NAV ITEMS */
    $('.exclude-me,.exclude-me a').addClass('exclude');
    $('.sqs-svg-icon--list a,.SocialLinks-link').addClass('exclude');

    /* REMOVE OTHER LANGUAGES AND KEEP EXCLUDED ITEMS */
    $('.multilanguage:not(".lang-'+lang+',.exclude")').remove();


  });
</script>

When I remove  the this part   /* REMOVE OTHER LANGUAGES AND KEEP EXCLUDED ITEMS */ it shows me the english menu, so something is happening, but I can't figure out why it isn't showing the german menues..

any one?