CSI-RS resource set with 4 resources of 1-port CSI is for beam refinement?
And CSI-RS set with 8-port CSI is for PMI report?
There is case where one to one mapping between CSI-reference signals and CSI-ports (not antenna elements).
Keep in mind that most AAU are hybrid antenna meaning weighting of beams it happens both in digital and analogue.
So for CSI-RS reference signals for PMI are transmitted from one csi-rs port that is connected to one logical antenna.
But that logical antenna can be connected to several antenna elements each having analogue phase shifting for beamforming.
We are not sure about this especially because csi-resources set with 1csi-rs port are with trsinfo = true meaning are trackign reference signals.
We also do not know how to identify that csi-rs beams are activated or not.
But nzp-csi-rs can be used for PMI reporting, beam management (csi-rs beams) and interference management in case of mu-mimo.