Found an answer in this answer.
add_filter( 'get_terms_args', 'wpse_53094_sort_get_terms_args', 10, 2 );
function wpse_53094_sort_get_terms_args( $args, $taxonomies )
{
global $pagenow;
if( !is_admin() || ('post.php' != $pagenow && 'post-new.php' != $pagenow) )
return $args;
$args['orderby'] = 'slug';
$args['order'] = 'DESC';
return $args;
}
The order may be ASC or DESC, and the orderby can be:
countdescription(it should, but didn’t work so well for me, futher tests necessary)nameslug
Plugins of interest
(may we call those Plinterests?)
The first two are very short and and can be easily incorporated into your code.
-
Category Checklist Expander : expands the height of the category list, so no scrolling is needed
-
Category Checklist Tree : this one rebuilds the Category Meta Box, so you can modify its code for further styling/adapting the box – and here’s a screenshot of what it does

-
Gecka Terms Ordering : creates an auxiliary table in the database (
wp_termmeta) to deal with the ordering. Has drag and drop capabilities.