My father was born to a French woman but adopted shortly after birth by Americans. My father died young, before the expiration of the 50 year restriction mentioned in 30-3 of the civil code. I am only 30 years old. My question is, will this 50 year limit still pertain to my father, even though he died well before 50 years expired?
Some courts decisions I read when preparing my answer to Will it be possible to get French citizenship? suggests that the 50-year delay is counted from the date you try to get your citizenship recognised. Even if the wording of article 30-3 is slightly different, that's also what article 23-6 suggests.
Under this interpretation, the question becomes “Has your father held ‘possession d'état’ or resided in France in the last fifty years?” and the answer is clearly no, even if he was already dead during some part of that period.