Moving a number of fields into a table on D7 node form
There is an API that will allow you to alter the output of the field group or write your own field group handler. https://www.drupal.org/node/1017962 

Using this you could write a custom field group handler that loops through the fields and outputs the data using theme_table(). This would allow for you to grab the field label and add it to the header array, and then add the fields to the the data array. 

After creating your custom field group you can nest the field group under the horizontal tab and nest your fields under the custom group.