Get node values from array with Drupal API?
If it is for page view of some kind, I think you can maybe try for this more robust way of getting at field values:

$output = field_view_field('node', $node, 'field_name');


An important trick that shows one of the ways to deal with field data properly. Initially  learned a while back off this site.

Another method of getting at the data I just thought of and use quite a bit in a recent project is entity api. Highly recommended add-on.
Consider the following borrowed snippet that shows how to deal with mail field. Other fields are the same.

   $wrapper = entity_metadata_wrapper('node', $node);
   $wrapper-&gt;author-&gt;mail-&gt;value();

To update the user's mail address one could use

   $wrapper-&gt;author-&gt;mail-&gt;set('stefp@example.com');

   or

   $wrapper-&gt;author-&gt;mail = 'stef@example.com';


Last but not least, there are still yet other alternatives surely?

Best practice for language key for &quot;und&quot; in hook_form_alter.  I did not flag as duplicate as I did not check into detail if other question was detailed or not, but it should be enough to give you ideas.

Good-luck.