This is listed in the city's open data as Delmar Path (see https://data.cityofberkeley.info/dataset/Trail-map/r3zb-4nu7 for example), and you can see the existing right of way in the parcel data.  It looks like the BPWA was raising money to build this path as recently as 2019 ( https://www.berkeleypaths.org/pathstories/2019/3/29/gofundme-campaign-for-terrace-view-paths ).  I don't know the current status of these efforts, but it seems reasonable to have this tagged as a proposed way.