[sbkp]

Maybe I missed something, or maybe it's that I'm on an old version. But in 4.0.17, to get access to $lng variables from product descriptions, I needed to insert the following in include/func.php:

after this code

  $page_content = $templater->get_template_vars("page_content");
  if (!empty($page_content)) {
    if (preg_match_all('/\$lng\.([\w\d_]+)[\}\s`\|]/US', $page_content, $preg))
      $variables = array_merge($variables, $preg[1]);
  }

added the following:

  $product = $templater->get_template_vars("product");
  if (!empty($product)) {
    if (preg_match_all('/\$lng\.([\w\d_]+)[\}\s`\|]/US', $product['fulldescr'], $preg))
      $variables = array_merge($variables, $preg[1]);
  }

Then I'm able to use any {$lng.xxxxx} in a product full description.