The Earth Book In Two Timelines

In our timeline, The Earth Book Of Stormgate is entirely written by Poul Anderson in English. In the Technic History, the Earth Book is multi-authored and is edited by Hloch of Stormgate Choth, presumably in both Planha and Anglic editions. (I imagine that, in that period, an AI program can translate instantly and satisfactorily.) 

When we read these stories not as originally published in Analog etc but as collected in the Earth Book with Hloch's introductions and afterword, we learn much more about each of the twelve individual texts. 

The Man Who Counts features van Rijn and introduces Sandra Tamarin. Van Rijn, Sandra and their son, Eric, play important roles in the later novel, Mirkheim.

"Day of Burning" introduces the Merseians who are important, to say the least, in the later Flandry period.

"Lodestar" introduces the planet, Mirkheim, not yet called that, and van Rijn's granddaughter who marries David Falkayn. Both the planet and the granddaughter/wife are important in Mirkheim.

"Wingless" and "Rescue on Avalon" introduce the Falkayn-led human-Ythrian colony on Avalon which will resist the pre-Flandry Terran Empire in The People Of The Wind. "Rescue on Avalon" introduces the surname, Holm, which will be important in The People Of The Wind when, among other things, Christopher Holm/Arinnian of Stormgate marries Tabitha Falkayn/Hrill of Highsky.

The "What Happened After" stories become larger scale.