At the moment this scenario with multiple templates support has been available only for the pure NativeScirpt ListView
For your convenience, I have logged a new feature request
for supporting this feature for RadListView
control, where the other users could vote for it.
if there is an interest for such a feature, this functionality will be available for some of the next "nativescript-telrik-ui"
For further info, you could keep track on the issue for further info.
Telerik by Progress