If you are not happy with the server, you just move to a different service and get your domain to point to the new server.
I’m just learning about takahe now, but it very much looks like domains are the remit of server admins, not users. Setting up a domain appears to require admin-privileges on the computer running takahe, not something that an individual user or non-admin group of users can do. So it seems to me that takahe doesn’t facilitate users controlling domains and improving mobility of domains between different servers controlled by different admins, but rather appears to be a tool for a given admin-team to segment their users and move them around among the group of servers they control.
I could very much be missing something here, this doesn’t seem to be a scalable approach to server mobility or a way to extricate yourself from an admin team you’re in conflict with.