Unable to retrieve any child terms using get_terms

Try relying on the new WP_Term_Query() class, here’s an example per your code:

 // WP_Term_Query arguments
$args = array( 
                'taxonomy'  => 'carabana_Cat', 
                'hide_empty' => false, 
                'orderby' => 'description', 
                'child_of' => 28) 
                );

// The Term Query
$term_query = new WP_Term_Query( $args );