Small hook to make field form elements translatables without i18n_field.

MYMODULE.module

<?php

/**
 * Implements hook_form_alter().
 *
 * Allow all field_* form fields title and description to be translated.
 */
function MYMODULE_form_alter(&$form, $form_state) {
  foreach (element_children($form) as $key) {
    if (strpos($key, 'field_') === 0) {
      $lang = $form[$key]['#language'];

      // Make root element title, description and options translatables.
      _MYMODULE_form_element_translate($form[$key][$lang]);

      // Make each delta title, description and options translatables.
      foreach (element_children($form[$key][$lang]) as $delta) {
        _MYMODULE_form_element_translate($form[$key][$lang][$delta]);

        // Make each delta's subelement title, description and options
        // translatables.
        foreach (element_children($form[$key][$lang][$delta]) as $subkey) {
          _MYMODULE_form_element_translate($form[$key][$lang][$delta][$subkey]);
        }
      }
    }
  }
}

/**
 * Helper to make a form element translatable.
 *
 * @param array $element
 *   The form element to make translatable.
 */
function _MYMODULE_form_element_translate(&$element) {
  if (!empty($element['#MYMODULE_translated'])) {
    return;
  }
  $element['#MYMODULE_translated'] = TRUE;

  if (!empty($element['#title'])) {
    $element['#title'] = t($element['#title']);
  }
  if (!empty($element['#description'])) {
    $element['#description'] = t($element['#description']);
  }
  if (!empty($element['#options'])) {
    foreach ($element['#options'] as $key => $value) {
      $element['#options'][$key] = t($value);
    }
  }
}