Basic location data (city, state, country) is in the rWHOIS data associated with the tunnel's IPv6 assignments, per RIR requirements, and suitable for use by external tools. IPv6 assignments are also from a pool specific to a tunnel server, and those have never been re-used or moved between servers.
That said, GeoIP vendors tend to use their own heuristics to determine location, and not use public information. Additionally, tunnels, due to their very nature, tend to create errors in those heuristics. For example: latency checks can be off if your location is widely divergent from the tunnel server, or your ISP's connectivity to us is not close to either your IPv4 side or the tunnel server.