What Is New In The Earth Book?

In Poul Anderson's The Earth Book of Stormgate, how much history does the editor Hloch himself impart? On Earth Real. all twelve Earth Book instalments had been published previously. Thus, in our reality, only Hloch's contributions are new. In the Technic History, however, only seven of the instalments had been published previously:

"Wings of Victory" in Far Adventure by Maeve Downey;

"Esau," "The Season of Forgiveness" and "Wingless" by Judith Dalmady/Lundgren, all published in the Avalonian periodical, Morgana;

"Margin of Profit" and "Rescue on Avalon" in Tales of the Great Frontier by A.A. Craig;

The Man Who Counts, a historical novel originally published on either Terra or Hermes.

By contrast 

"The Problem of Pain" was part of a private correspondence preserved in the University of Fleurville on Esperance;

"How To Be Ethnic In One Easy Lesson" was part of the private reminiscences of James Ching;

"A Little Knowledge," "Day of Burning" and "Lodestar" were specially written for the Earth Book, the latter two co-written by the editor.