Render Selected Categories in Admin Edit Post Screen differently

Selected Categories for a post in the admin screen are rendered by:

// Put checked cats on top
$output .= call_user_func_array( array( $walker, 'walk' ), 
array( $checked_categories, 0, $args ) );

in \wp-admin\includes\template.php (around line 163)

I would like to, for the selected one on top, instead of displaying category “jkl”, render the full hierarchical path behind it, like so: “jkl (abc\def\ghi\jkl)”, how ? (thinking of either custom taxonomy or custom box (hide original) or jquery, find the div, replace the div with ajax call).