What is the current state of the law in Canada where documentary evidence of the marriage is weak?

Counsel referred me to cases where courts have relied on oral testimony concerning the marriage in order to recognize marriages (usually outside Canada) where documentary evidence of the marriage was weak. However, those authorities addressed only the evidentiary requirements to prove a marriage, and not whether the marriage sought to be proven was a valid marriage under the law of the jurisdiction where it took place: see, for example, Porteous v. Dorn , 1974 CanLII 157 (SCC), [1975] 2 S.C.R. 37.