Inline Entity Form – How to change label for the EDIT button and REMOVE button

I try to modify the ‘Edit’ and ‘Remove’ label on the buttons displayed in the IEF table.
I can modify the ‘Add new node’ buttons with the code bellow

function MY_MODULE_form_alter(&$form, &$form_state, $form_id) {
  if ($form_id == 'CONTENTTYPE_node_form') {
    /*
    * Modify the Add node button when it's the first one
    */
    $form['MY_FIELD']['und']['form']['actions']['ief_add_save']['#value'] = t('CUSTOM TEXT');
    /*
    * Modify the Add node button when there is at least one node
    */
    $form['MY_FIELD']['und']['actions']['ief_add']['#value'] = t('CUSTOM TEXT');
  }
}

But I can’t make it work for the Edit or Remove buttons

For the Edit button, I tried to add in this function:

$form['MY_FIELD']['und']['form']['actions']['ief_entity_edit']['#value'] = t('CUSTOM TEXT');

Doesn’t work

$form['MY_FIELD']['und']['actions']['ief_entity_edit']['#value'] = t('CUSTOM TEXT');

Doesn’t work either

Any idea ?