Ok, let me know if this doesn't answer your question. When you use a content-option, the page that is selected is stored as a page:id such that the page can be accessed directly by a keychain.
For instance, you can access the page title of the chosen page by using data:Instanzen>first>page:title. If you wanted some scaffold data on the page named "fieldx" then you would use data:Instanzen>first>data:fieldx. ("first" has to be there to remove the square brackets from the output of a list (it is kind of treated like an array output but for some reason the returned value still has the square brackets, this has caused many problems).
So, in your report you just need to do a local reporter with data:Instanzen>first as your key. Hope this helps.