Dear Secondary Mover —
God had only outlined one sin for Adam and Eve, and it was mortal. So there was no venial sin to commit.
Of course, they could have repented — God gave them multiple opportunities.
First he said, "Where are you?", to invite them to "fess up voluntarily". That did not work.
When God then confronted them, instead of asking for mercy and confessing what they did, Adam — blamed it on God. Eve blamed it on the serpent. Neither took responsibility. If they had though, It's a matter of speculation what would have happened.
In the last analysis, however, speculating about what would happen in a non-existent "time line" is somewhat pointless.