AF: Your question is far too technical for an open forum like this - it may yield answers not professional enough. The design team should look for certification specifications in appropriate documents such as FAR part 25 or/and EASA CS-25 ... which I am sure they do.
My last type specific LVO training was done by an ex-SAS examiner inhouse at Toulouse Airbus training center on a CAT IIIB aircraft. The advised course of action for autoland problem below minima was to DECIDE. If the real situation provides enough visual cues, it is entirely possible for the captain to land; and it is legal. If the captain does not see (s)he will go around and everybody understands that the gear will touch down during the manoeuvre. Both options are available. The key point is the term enough visual cues.
Take care,
FD (the un-real)
PS: As I proposed, my contribution may yield answers not professional enough.