What a great way to cross-check. Good thinking.
I assume you're checking against the online index GeneSA, launched 2012.
A few thoughts:
You've allowed for the Latin spelling of their names?
Do they appear in the older CDROMs by Gould?
Apparently the Gould data was hand-gathered (using a blunt term), from many sources. And the new online GeneSA database was loaded directly from the Govt. BDM, instead of the in-house SAGHS - this according to the information SAGHS gave me.
Maybe, at the time the established socio-religious habits stuck fast. Another baby arrives, it is registered when the next RC father visits your locality - miles from anywhere!!
I've been told that the visiting clergy (any faith) were to send into Adelaide (or other Civil Reg. centres) a return of the registrations on some periodic basis. In short the clergy were voluntary collection agencies and clerks for SA Govt BDM. I should read up on that, somehow, to see what the arrangements were.