WordPress at a glance
action is not described

manage_comments_custom_column action-hook . WP 2.8.0

Fires when the default column output is displayed for a single row.

Usage

add_action( 'manage_comments_custom_column', 'action_function_name_8746', 10, 2 );
function action_function_name_8746( $column_name, $comment_ID ){
	// action...
}
$column_name(string)
The custom column's name.
$comment_ID(int)
The custom column's unique ID number.

Where the hook is called

WP_Comments_List_Table::column_default()
wp-admin/includes/class-wp-comments-list-table.php 794
do_action( 'manage_comments_custom_column', $column_name, $comment->comment_ID );

Where the hook is used (in WP core)

Does not used.