Now you are able to find it out via Nominatim.
There was a need to have something to tag highlands and landscapes. So there is now this first draft of a proposal.
I hope there will be discussions about that. If you find some tagging proposals related to this, please let me know!
PS: There are also Teutoburger Wald, Bremer Schweiz, Wesergebirge and Wiehengebirge available with this tagging.