Nice! I have some reservations about some of the data though; f.ex. I have a hard time to believe that SF has only slightly higher costs of living than Berlin.
It really depends, the NomadCost is based on staying there for a month, and not being able to rent long-term. So you'll be staying in private rooms in hostels, low-end hotels and CL/AirBnB apts. Finding a cheap place in East Berlin for a long-term is definitely a viable option. But not if you move around as fast as digital nomads do.
Have you thought about crowdsourcing the data entry?