WPMU: Programmatically adding CPT posts to specific blog id

I finally found the answer myself. It’s two parts:

1. I need the global $switched to be defined.
2. The variable for blog id can’t be $blog_id because that’s reserved.

The above code should thus be the following.

require_once( "../wp-load.php" );

global $switched;
$blog_id_target = 2;
switch_to_blog($blog_id_target);

$lang = 'en';

$new_pr = wp_insert_post(
    array(
        'post_author'   => 1,
        'post_status'   => 'publish',
        'post_type'     => 'pressreleases',
        'post_date'         => $this->publish_date,
        'post_content'      => $this->body,
        'post_title'        => $this->title,
        'tax_input'         => array(
            'pr_categories'     => $this->pr_category_id
        )
    )
);
var_dump( get_current_blog_id() ); // This returns (int)2, just like it should.
restore_current_blog();