Hello @kevbrown044,
Thank you for getting in touch with us!
We haven’t tested that plugin with the CartFlows but let me tell you that if you delete the thank you page of the Flow, then the CartFlows will redirect you to the default thank you page of the WooCommerce.
But if you delete the CartFlows thank you page as well as default WooCommerce’s thank you page, then it might redirect you to the custom thank you page but not entirely sure it will work or not.
Also, we have added the redirection option on the backend setting of Thank you page of the CartFlows. You can give the link of your custom thank you page. Using this option, once the user comes on the CartFlows thank you page, he will be redirected to the custom thank you page.
I hope this helps.
Please let me know in case you have more questions.