D7: Import localized menu programatically
You dont need to play directly with i18n. All you need is the correct configuration.
It also has a difference between translated and localized items. Translated items may point to different pages and may have different description (besides other customization). Localized item is the same item with just a different title on the menu for each language.

I think you want a translated item. Here is the recipe with some comments:

 &lt;?php 
 $menu_item = array(
    'link_title' =&gt; 'The menu link title',
    'menu_name'  =&gt; 'machine-name-of-the-menu', // It uses '-', not '_'
    'customized' =&gt; 1, // Must be 1 in order to not dispaly the link in any language
    'link_path'  =&gt; 'node/' . $node-&gt;nid, // menu_link_save() does not like aliases. Then 'nid' is used
    'language'  =&gt; 'en', // language is required in order to make the item translatable
  );
  $mlid = menu_link_save($menu_item); // You don't need to receive it in a variable
  $ml = menu_link_load($mlid); // I'm loading $mlid just to display the result and verify it
  print_r($ml); // Use print_r() only if you are testing on the block "Execute PHP"


I had a hard time to figure out the need of 'customized' and also the path alias issue.