Untold Stories?

An author might create more background material for a work of science fiction than appears in the text. For example, a planetary ecology requires more globally interacting geographical areas and local environments than the hero is likely to encounter while traversing the planetary surface. Thus, the Author's Note to Poul Anderson's Virgin Planet discloses details about an uninhabited continent that remains unvisited during the novel.

Robert Heinlein's Future History Time Chart presents data, like an Antarctican Revolution, that do not appear in any of the stories and even lists in brackets six "stories-to-be-told" that never did get told. Might there be some such untold stories in Anderson's Psychotechnic History? Of course, none are listed in the Chronology. However, Anderson tells us that he:

compiled a Heinleinian chart of story titles;
occasionally wrote a story corresponding to one of the titles;
eventually did not complete the series but merely gave it up.

So there might have been more titles on his original time chart? The opening story mentions but does not feature Valti, the founder of psychotechnics. The Traveler crew had many adventures before colonizing Harbor. One involved riding and talking with centauroids en route to attack their winged enemies' aerial city. This adventure is mentioned again but not recounted. We learn that the centauroids, birds and flying city were on the planet Aesgil IV. But we would like to read that adventure.