Nuance in adding CPT and TAX to a submenu

I’ve answered a similar Question. AFAIK, you have to solve it with jQuery.

var reference = $('#my-draft-posts').parent().parent();

// add highlighting to our custom submenu
reference.addClass('current');

//remove higlighting from the default menu
reference.parent().find('li:first').removeClass('current');

And the trick is to add an ID in your custom menus, so you can reference them.

add_submenu_page(
    'edit.php',
    'Drafts', 
    '<span id="my-draft-posts">Drafts</span>', // <---- HERE
    'edit_pages', 
    'edit.php?post_status=draft&post_type=post'
);

Much probably, you’ll need more jQuery than this sample.