I've been trying to figure this out but am in over my head.  What I've got is a repeating field with two fields in it - an upload field, and a text field.  What is in the text field needs to be added to the image meta as the alt text. So far, I have this: 

add_action('frm_after_create_entry', 'add_uploaded_file_alt', 30, 2);
add_action('frm_after_update_entry', 'add_uploaded_file_alt', 10, 2);
function add_uploaded_file_alt( $entry_id, $form_id ) {
if ( $form_id == 3 ) { //3 being create post/front end editor form
$media_ids = array ($_POST['item_meta'][88]); //88 being upload field id
$alt_text = array ($_POST['item_meta'][91]); //91 being alt text field
$img_meta = array_combine($media_ids, $alt_text); 
foreach ($img_meta as $id => $alt) {
update_post_meta( $id, '_wp_attachment_image_alt', $alt );
}
}
} 

However, I'm not getting any results for $media_ids and $alt_text, from what Victor tells me, I need to add another array to loop through?  The results of print_r($_POST) are below, so you can see what I am working with.  Can you fix my code?  $50 bounty via PayPal? Here's the post array: 

Array   (   [frm_action] => update   [form_id] => 3   [frm_hide_fields_3] =>   [form_key] => add-article   [item_meta] => Array   (   [0] =>   [11] => Testing 382   [12] => <!-- wp:shortcode -->   <p>[display-frm-data id=64744]</p>   <!-- /wp:shortcode -->   [13] =>   [14] =>   [23] =>   [22] =>   [16] => 3   [28] => 0   [25] =>   [17] => 1   [84] =>   [15] => draft   [89] => Array   (   [form] => 9   [row_ids] => Array   (   [0] => i448   [1] => i449   [2] => i450   [3] => i452   )       [i448] => Array   (   [0] =>   [88] => Array   (   [0] =>   [1] => 64763   )       [91] => mother's day flowers test1   )       [i449] => Array   (   [0] =>   [88] => Array   (   [0] =>   [1] => 64764   )       [91] => McDonalds Burger test2   )       [i450] => Array   (   [0] =>   [88] => Array   (   [0] =>   [1] => 64765   )       [91] => which iPhones are waterproof? test3    )       [i452] => Array   (   [0] =>   [88] => Array   (   [0] =>   [1] => 64767   )       [91] => test 4 tip it forward   )       )       [32] =>   [80] =>   [29] =>   [36] =>   [63] =>   [90] =>   [key_pointer] => i452   [parent_field] => 89   )       [frm_submit_entry_3] => a327d92cf9   [_wp_http_referer] => /edit/?frm_action=edit&entry=444   [id] => 444   [item_key] => 2f4d0   [frm_state] => LZeN1XPAlwqHMyJlcMUjSWmNTvvIRWXKTfraM2Tq4GA=   [item_name] => Testing 382   [frm_user_id] => 1   [frm_skip_cookie] => 1   )