IMHO the wording may be interpreted as enabling AFCS coupling but requiring the navigational position to be verified with an approved aid.
You, the pilot, control the aircraft either via the AFCS (AP/FD) or with manual flight, this includes navigation. You establish the navigational position of the aircraft whichever nav aid is chosen for ‘primary’ use; – the AFCS does not decide the position or the nav aid’s accuracy.
In practical terms I would strongly advise against coupling to the AFCS, and in situations where there are few if any precision nav aids, do not even display the FMS on EFIS.
The rationale for this is that the use of AP or the EFIS indications might inadvertently distract the crew from the approved nav aid as usually the AP and EFIS are the most prominent cues..
My experience of this was with a long range nav aid subject to drift, not approved for approaches, but still ‘navigating’ during a remote area NDB approach. Both the FMS and ADF were displayed on EFIS; this resulted in high mental workload to ignore the ‘dominant’ FMS symbols. The AP was used in the hdg mode; the FMS was incorrect by at least 2nm – only verifiable when visual.