If those variables are not enough to trigger your conditional logic, you will likely have to make your own email templating system. The email templates we provide are a on-size-fits-all pattern, and obviously some use-cases will be missed with that type of compromise.
To make a fully customized setup, you could create a backend service that does your conditional logic, calls the management api verification ticket endpoint to generate a url with your desired redirect, then sends the url in a verification email via a email provider of your choosing. You could call this service from a rule or hook on first authentication or signup with the info you desire.
Email redirects are something we have talked about quite a bit and we would like to get more feedback from you on the subject. If you could please describe your use case to our product team through our feedback page that would be very helpful. We use this info to implement new features in our product.
In addition, if you would like to describe your use-case with us, we could potentially provide some guidance. I understand that the conditional logic in the RedirectTo field is not sufficient for your redirects. Could you describe in more detail how you want the redirects to change?