Seraphim are clearly ~low top tier, so I propose the following powerscaling convention
Peak top tier = Pirate King level
High top tier = Yonko/Fleet Admiral level
Mid top tier = Admiral level
Low top tier = Seraphim level
Are you saying that Nami, Usopp, Lanji, Robin and Franky survived a prolonged fight against a top tier? They did better than all of the injured scabbards, Momo and Yamato against a top tier.
When Zoro solos Kuma in the next few chapters we're gonna have a BBQ in here.