Label form element is duplicated due to #group naming overlap

+++ b/translators/tmgmt_file/src/FileTranslatorUi.php
@@ -88,14 +88,14 @@ class FileTranslatorUi extends TranslatorPluginUiBase {
     $form = array(
-      '#type' => 'fieldset',
+      '#type' => '#markup',
       '#title' => t('Import translated file'),
     );

That makes no sense at all ;) There is no such thing...

Basically, looks good now.
I'm just wondering about this:

+++ b/src/Form/JobForm.php
@@ -317,7 +317,7 @@ class JobForm extends TmgmtFormBase {
     if (!$job->isSubmittable() && empty($form['translator_wrapper']['info'])) {

On the following line as well. Shouldn't we edit that to checkout_info as well?

As discussed, that text should appear in case the translator plugin returns, for example, an empty array. So update those as well.

Double Post, pls ignore.

Can you please provide a test-only patch that shows the bug happens?

A test with a translator that doesn't supply any checkout information is probably unnecessary. I'd say this patch is ready for commit.

Committed.