Maxmind data is also often just wrong, updated or not. As a hosting provider with a number of IP ranges, we have to deal with submitting corrections to them, Google, ip2location, etc. all the time. Not sure why none of them seem to use very accurate methods to discern IP location.

Since you're doing a traceroute anyhow, you'd be better off analyzing the transit hops, and specifically the city codes used in the reverse DNS entries.