Hi Chouby, sorry for the late reply but have been away for a day.
When I activate the languages management for the Custom Post Type (products) and for the Taxonomy (shop-category) I get this message from Chrome: "This webpage has a redirect loop".
Also, is it necessary to activate both the CPT and Taxonomy if I don't want to use translations for my Shop section?
With my "Videos" Custom Post Type and "Videos Categories" Taxonomy I got the same identical set in the functions.php, only the name change. I remember that the Videos CPT and Tax. hand the same problem at some point, than by working on it I was able to make it work (except for the Taxonomy highlight thing).
Also, you can notice that on the page "http://manonuda.com/videos-categories/showreel/" on the top of the content area there is "List of videos for: English". That should be the name of the taxonomy term, but with Polylang activated it writes "English" not the term.
Here is the code:
<?php if( get_post_type() == 'mnd_videos' && !is_front_page() ) { ?>
<?php
// from: http://wordpress.org/support/topic/equivalent-of-single_cat_title-for-custom-taxonomy-archive-page?replies=5
$termname = $wp_query->queried_object->name;
echo '<h2 class="archive-title">List of videos for: <span>"' . $termname . '"</span></h2>';
?>Anyway, thanks for the help.