First please check if you translated those texts in .po file in wp-content/themes/woopress/languages directory. If you did but translation doesn’t show you need edit the files:
“Add to Wishlist” can be found in wp-admin panel > YIT Plugins > Wishlist > General Settings > “Add to Wishlist” text.
“Return to Previous Page” is placed in wp-content/themes/woopress/framework/theme-functions.php (line 3276).
“Product Description” text is in the file wp-content/themes/woopress/woocommerce/content-single-product.php (line 107).
“Email to a friend” is present in wp-content/themes/woopress/framework/woo.php (line 861).