This repo is pretty outdated and actually that current default might even have been only for testnet. There are more active seed nodes listed in hsd and we are adding more to hnsd. The problem with using these with hdns is that they are essentially trusted nodes (clients trust them to verify proof of work). For clients like federalist it may make more sense to integrate hnsd directly. Otherwise, users should configure this library to connect to a node they trust (i.e. they run it themselves)