You must actually physically go to the location and discover the fast travel point there. Cartographer will not get this for you.
"All locations" means places with a fast travel point:
Cities: Rattay (upper and lower gate), Ledetchko, Sasau, Monastery, Neuhof, Uzshitz, Samopesh, Rovna, Merhojed, Talmberg, Skalitz.
Bandit camp cities: Pribyslavitz, Vranik
As well as Rattay Mill and Inn at the Glades.