Punishment from a twenty-year-old

To the Honorable Gaon Shlita,
Here is how the decree to die in the wilderness was made clear, only to those who were twenty years old. It is explained in the Book of Judges that the highest court does not punish anyone except those who are twenty years old. This is a statement by the Lord, the Lord, who is less than ten years old.
And it is stated in the instructions of the 8th chapter that one does not bring a sin offering by mistake, except for a matter in which one has committed adultery, and it is explained in the Book of the Sabbath that a minor less than twenty years old is not punished by heaven and is not a child of the covenant. How does one bring a sin offering? One does not bring a sin offering except for a matter in which one has committed adultery.
With loyal regards,
Young learners