What this source establishes
Read the hedge, because Besse meant it. Writing in 1914 with the mission's archives before him, he does not say de Britto built the church — he says the builder IS SAID TO BE de Britto, and the year 1685. Two sentences later he marks his own dividing line, “Here tradition is met with historic documents”, and only then produces the Annual Letter of 1701. So this page proves the attribution was already old and archived, not that it is true. The moment's documented tier rests on Hardgrave and Pate, not on this sentence.
This is as much of the book as this site prints. It is named in full in the bibliography below.