WooCommerce theme overload problem

Hello,

– Theme used: Alterna V9 (http://themeforest.net/item/alterna-ultra-multipurpose-wordpress-theme/3946450)
– Extensions : WooCommerce
– Site address: http://www.jsarc.fr

Problem encountered :
I installed the WooCommerce extension and pay a theme called Alterna. This includes new pages to “overload” WooCommerce plugin (I mean add new features), including:
– wp-content / themes / alterna / woocommerce / wooCommerce-config.php
– wp-content / themes / alterna / woocommerce / topbar-cart.php.
I wanted to change some details on these pages and have created a child theme with the same personalized pages:
– wp-content / themes / alterna-child / woocommerce / woocommerce-config.php
– wp-content / themes / alterna-child / woocommerce / topbar-cart.php

The change is to add a small icon and to translate the word “cart” in “panier” (french) in the top bar which is on the top-left corner. The problem is: my child theme seems taken into account but only for a fraction of a second before the parent theme returns…
You can see it on the site’s home page: http://www.jsarc.fr.

Would you be able to help me solve this problem?

Here is the content of the pages in question :
– wp-content / themes / alterna / woocommerce / woocommerce-config.php :

[ Excessive code moderated ]

Thanks a lot for help =)