Cubase Studio was a lower edition of Cubase than just “Cubase” - it is rather like Cubase Artist today compared to Cubase Pro. As Cubase Studio is not listed amongst the qualifying products, I cannot see that you can crossgrade directly to Nuendo.
I believe you only route to use your Cubase Studio licence to get Nuendo would be to upgrade to Cubase Pro, then crossgrade to Nuendo. It will probably be cheaper to buy an old licence for Cubase / Cubase Pro, then crossgrade that - though prices on these old licences seem to be rather high at the moment because of interest from possible Nuendo crossgraders.