That's what I have in the editor, screenshot also attached. I've tried adding it in CS Cart through the template editor (version 4.3.2) and then through CPanel editors.
I also tried adding the variable as per your code.
Adding the script tags before isn't working for me.
TrustPilot tell me it's the + within the <script type="application/json+trustpilot"> which is being changed to <script type="application/json+trustpilot"> when the email sends.
This really should work on e-mail, it's the one unique identifier which can't be changed.
We run a 10% off your first order promotion. A customer has just placed an order with the usual email but has changed billing and shipping address, they now have 10% off for their 7th order with us.