That’s fine, except that some family names including RRDJ member names would have already established crests/CoA having been previously recorded in the English College system. I suppose the chances of conflicting recorded crests or names is fairly remote.   

What difference would it make to you if there was an identical crest in papua New guinea?

What legal standing, if any, does RRDJ or its official documents have in an Australian court room?

What exactly is an Australian courtroom?

(I understand that the seal of Sir John is not regarded as an Australian registered notary.)

You are under a misunderstanding.