Humans did the writing, but their writings have a supernatural origin, and it's the same with Maria Valtorta. Therefore, since you say it's a logical fallacy for me to believe the writings of Maria Valtorta, then you should stop believing the writings of the ancient prophets, or the four Evangelists, and so on. If you want to avoid displaying a double standard that is.
However, what you believe Jesus wrote on the ground isn't so, but rather it was the sins of the adulterous woman's accusers:
« Usurer »
« False »
« Irreverent son »
« Fornicator »
« Murderer »
« Desecrator of the Law »
« Thief »
« Libidinous »
« Usurper »
« Unworthy husband and father »
« Blasphemer »
« Rebellious to God »
« Adulterer »
and then He said, "If there is one of you who has not sinned, let him be the first to throw a stone at her."
He had done this because there was a lack of charity and sincerity in the accusers. Not because they lied in accusing. The woman was really guilty. But they were insincere being scandalised at something they had committed thousands of times and that only greater cunning and better luck had allowed to remain concealed. The woman, at her first sin, had not been so cunning and lucky. But none of the accusers were free from sin. One ought to be free from sin in order to condemn with justice.
Jesus was not unaware of the hearts of those Pharisees and scribes, or of the hearts of those people who had joined them in insulting the guilty woman. Sinners against God and their neighbour, they had sinned against faith, against their parents, against their neighbour and above all they had committed many sins against their wives. If by means of a miracle He had ordered their blood to write their sins on their foreheads, among the many charges that of "adulterers" by deed or by desire would have reigned supreme. Jesus has said: "It is what comes from the heart that contaminates man". And with the exception of His heart, there was no one among the judges whose heart was pure. They lacked sincerity and charity. Not even their being like her in their hunger for lust induced them to be charitable.
It was Jesus Who was charitable to the dejected woman. He, the Only One, Who should have been disgusted with her. But remember this: "The kinder one is, the more compassionate one is to culprits". One is not lenient to the fault itself. No. But one is indulgent to weak people who have not resisted temptation.
Jesus could've stoned her, and it would've been just, because she really was guilty as He confirmed, but it wouldn't have been mercy. By saying "Neither do I condemn you. Go and sin no more", He gave the adulterous woman time and possibility to arrive at repentance and holiness, if she wished to reach them.
No matter how guilty a man is, he is to be treated with respect and charity. You must not rejoice at his annihilation, you must not be pitiless, not even with curious glances. Have mercy on those who fall.
I wholeheartedly defend Maria Valtorta, because Jesus actually showed her the scene of the adulterous woman, among other scenes from His life on earth. See the chapters on proofs in
A Summa and Encyclopedia to Maria Valtorta's Extraordinary Work that are in support of her writings having a supernatural origin.