Chouby on "[Polylang] Touchfolio theme localization"

The problem is not coming from Polylang or from your translation in the .po file. It is a bug of the theme (you should report it to the author).
Edit the file at line 67 and replace

mobileMenu = $('<a class="menu-button"><i class="menu-button-icon"></i>menu</a>');

by

mobileMenu = $('<a class="menu-button"><i class="menu-button-icon"></i>'+dsframework_vars.menu_text+'</a>');