Error when setting Text.fontFamily

Correct. It works when in the same context but the error is thrown when applying to other contexts.
But I have been misunderstanding the edit context. I thought that you can edit anything in the current group and groups it owns but it appears that’s not possible?

However it sort of still works:

But it doesn’t save the changes when the dialog closes.

So I’m going to add a feature request and link it back here.