I think "anglo-american empire" accurately describes the core nations of the bloc, the vassalization of peripheral nations like Germany and RoK, and better highlights the historical nature of the bloc (i.e. how America essentially took over the UKs role as Imperial Hegemon).
I don't think it is possible to describe this political formation without being reductionist. I maintain "anglo-american empire" is more descriptive but I also think "English speaking world" is adequate.
english speaking world