There must be some type of rating because you are asked to rate coordinator after a trade. Maybe koalasat can give some insight. I have seen them post about robosats and coordinators and discussed nostr reviews. nostr:nevent1qqsznrurv6cms4nmgtjdy2udwz0lfd5mhu0zsdr20f627r3xumhh75qppemhxue69uhkummn9ekx7mp0qgsxg45ph8gx0vdrvtzta6xal7v86frx6jvstsnvhrlvtehmwwh4epqrqsqqqqqp6ldaya
There is actually no rating ATM. What you vote at the end of the trade is just feedback to the coordinator, but it's not shared (that info is stored in the coordinator itself and it might be tricked). That said, I'm working on integrating nostr in some parts of RS and one of those is to create a coordinator rating system where none of the 3 parts (federation-coordinator-user) has to trust each other https://github.com/RoboSats/robosats/issues/1097