Please note that you can use either ports or packages on one base system. Using jails you can use for example ports in one jail and pkg in a different jail. ports-mgmt/synth has the goal to allow using ports with non default settings. Ports with default settings can be fetched as pkg to reduce the compile time. I am not sure how far it works already. I just mention that because this is your first post and I am not sure if you are already aware of that.
I see. It would be more advisable to compile the unbound port, than to recompile the base-system build of unbound.
I have learned about the existence of unbound-control, though, which does everything I wanted to do with unbound's scriptable interface. I need to automate the frequent updating of a changing set of local-zones on multiple boxes. The scriptable interface now seems very overpowered and dangerous, and not something I want to let loose if I don't have to.