I was a catholic, and even I don't know exactly how to answer that question, but I will try. I had never heard of anything about being born from above, like in John 3. All I was ever told, was that it was much less serious to commit venial sins, I was told not to commit any mortal sins, though no one ever told me exactly what mortal or venial sins were. If I committed a mortal sin, I would lose my salvation. As I recall, the only ways to get salvation back, were to go sit in the little box and tell the priest my sins, or make a perfect act of contrition, but no one told me what that meant either. So, I guess you could say they had to be "reborn" an unlimited number of times, by going to confession. After awhile, I realized I was powerless to stop committing mortal sins, so I just gave it all up. 😇 I hope that helps.
You candor shines like a beacon over the stormy waves. Pray some see it and follow it to safe harbor.
a perfect act of contrition, but no one told me what that meant
According to the Catechism of the Catholic Church, contrition is called “perfect” (contrition of charity) when it arises from a love by which God is loved above all else. (CCC 1452)
It is differentiated from contrition that is called “imperfect,” which is born of the consideration of sins ugliness or the fear of eternal damnation and the other penalties threatening the sinner (contrition of fear). (CCC 1453)
If you are interested, mortal sin is described in CCC 1854 - 1864.