Try the following:
1. Open the "wp_eStore1.php" file and find the following block of code:
$cart_language = get_option('eStore_cart_language');
if (!empty($cart_language))
$language_file = "languages/".$cart_language;
else
$language_file = "languages/eng.php";
include_once($language_file);
2. Once you find it replace it with the following block of code:
function wp_eStore_load_qTranslate_lang()
{
$cart_language = qtrans_getLanguage();
switch ($cart_language)
{
case "en":
$language_file = "languages/eng.php";;
break;
case "it":
$language_file = "languages/ita.php";;
break;
case "de":
$language_file = "languages/ger.php";;
break;
}
if(empty($language_file))
{
$cart_language = get_option('eStore_cart_language');
if (!empty($cart_language)){
$language_file = "languages/".$cart_language;
}
else{
$language_file = "languages/eng.php";
}
}
include_once($language_file);
}
add_action('init', 'wp_eStore_load_qTranslate_lang');
3. Now, when you select a language from the qTranslate widget eStore will load the corresponding language file specified inside the "switch" statement.