No interpretation needed. Paul states clearly in scripture that if it wasn’t taught by them the teachings was to be considered accursed. The Catholic Church teaches many things they can’t prove the apostles taught.
Gal 1:8 But though we, or an angel from heaven, preach any other gospel unto you than that which we have preached unto you, let him be accursed.
Emphasis added, for Gal 1:8 does not say..
what the apostles taught rather the gospel they taught.
The former is a more nebulous term. In other words, if we take it as literally as you demand, then ONLY the GOSPEL can be known authoritatively. All else, all other facts about Christianity, such as the name of the mountain where Christ underwent the Transfiguration (Mt. Tabor, which isn't in Scripture, the name, isn't there), to yes, even events about Mary's life, can't be known with certainty.
It's lunacy to say that and in fact, it's not even what the Scripture says! The Scripture says the GOSPEL must be the same, not that EVERYTHING about everyone in the Bible needs to be IN the Bible for it to be true!
Events about Mary and her life, from her Title "Mother of God" to the dogma of the Assumption don't *contradict* the Gospel, they just simply aren't there, just like the name "Mount Tabor" isn't in Scripture either. But believing Mt. Tabor is where Christ underwent His Transfiguration doesn't *contradict* Scripture, just like the Title and Assumption of Mary don't either.
But go ahead, give me your opinion again to get that precious last word in, go ahead and "convince" me you aren't giving your *interpretation* of Gal 1:8, rather that its merely "speaking for itself", as you use your OPINION of Gal 1:8 as proof of that.