In Obi202 firmware 3932, (or possibly on 3878, not entirely certain), one part of this has started working.
For calls received with a blank CNAM, the CNAM field shows "UNKNOWN".
For calls received with *67, the CNAM field shows "PRIVATE CALLER". In this case rhe CALLER ID field still shows blank.
Curiously, the Obi Call History also shows blank for CNAM in both cases. The call is made to a GV number, but is coming in via CC, and CC's call history shows: Blank or "Anonymous".
Conclusion: Either the analog phone I've been using for ten years magically started inserting UNKNOWN or PRIVATE CALLER, or the Obi202 is now sending UNKNOWN or "PRIVATE CALLER" for CNAM, but does not enter either of these values in the Call History log.