Surely the requirement is that you don't descend before the FAF; if you allow for inertia of the aircraft selecting the target V/S or FPA at about -0.2nm should still not cause a descent below the platform altitude until the required point.
IR stuff sort of gets woolly around CDFAs as technically we should ensure that all platform altitudes are crossed at -0ft, but if this would destabilise the otherwise sensible CDFA then it can be less safe, thus examiner guidance is to exercise judgement.
Use of ROSE/ARC modes on ND during VOR approach: only caveat is that to use ARC mode NAV ACCY must be HIGH. If it isn't, switch to VOR ROSE mode (which is a far easier display to use if you are manually adjusting/monitoring tracking). If NAV ACCY is LOW then ARC has little useful info on it besides the needles as planned track and EGPWS info is compromised.
Not being allowed to adjust the selected FPA if you have deviated from the planned vertical profile makes no sense to me. Would you be allowed to adjust your V/S manually if you decided to disengage all AP/FD and fly the approach in raw data? Has the person who wrote this rule ever flown a CDFA non-precision approach at all, let alone in an airbus?