my custom module doesn’t seem to have an affect

I’ve created my 1st module. The purpose is to add the customer group name to the order email template. I think that I didn’t do something quite right and was hoping someone could look at my files to see where I may have messed up. The files are stored in magento/app/code/KeystoneCandle/AddGroupEmail/, /etc and /Observer

registration.php

    <?php
 
MagentoFrameworkComponentComponentRegistrar::register(
    MagentoFrameworkComponentComponentRegistrar::MODULE,
    'KeytoneCandle_AddGroupEmail',
    __DIR__
);

module.xml

    <?xml version="1.0"?>
<config xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xsi:noNamespaceSchemaLocation="urn:magento:framework:Module/etc/module.xsd">
    <module name="KeystoneCandle_AddGroupEmail" setup_version="1.0.0">
    <sequence>
        <module name="Magento_Catalog"/>
    </sequence>
    </module>
</config>

Observer file AddGroupEmail.php

<?php

namespace KeystoneCandleAddGroupEmailObserver;

use MagentoFrameworkEventObserver;
use MagentoFrameworkEventObserverInterface;
use MagentoCustomerModelGroup;

class AddCustomerGroupToOrderEmail implements ObserverInterface
{
    protected $_order;
    protected $_group;

    public function __construct(
        MagentoSalesModelOrder $order,
        Group $group
    ) {
        $this->_order = $order;
        $this->_group = $group;
    }

    public function execute(Observer $observer)
    {
        $order = $observer->getEvent()->getOrder();
        $customerGroupId = $order->getCustomerGroupId();
        $customerGroup = $this->_group->load($customerGroupId);
        $customerGroupName = $customerGroup->getCustomerGroupCode();

        // You can do additional processing with the customer group if needed.

        $order->setData('customer_group_id', $customerGroupId);
        $order->setData('customer_group_name', $customerGroupName);
    }
}

Then in the email template I try to use these variables to show the customer group name and ID

{{var order.customer_group_name}} {{var order.customer_group_id}} 

I’ve run setup:upgrade, setup:di:compile, setup:static-content:deploy -f, cache:flush/clean

The strange thing is that the

{{var order.customer_group_id}} 

variable pulls the customer group id even after I disable my module (and run all the previous commands) so I’m not sure if that variable needed the observer or not but I can’t get any reaction from the customergroupname. I’d appreciate any insights. Thanks.