before and will not repeat any observations that I remember making before although I might link to them if I can find them.
"Operation Changeling," the fourth "Operation..." story, was published in 1969 and was a commentary on the 1960s. Operation Luna, a long novel, was published exactly thirty years later and thus is of the same era as other later novels even though, in terms of content, it continues Anderson's series about the Matucheks in the goetic timeline.
Unusually, the text of this novel begins on p. 1. It is 438 pages in length with very little blank paper between chapters. The opening page has one word, "malpais," that I needed to google and one geographical reference, "Mount Taylor," that I found it helpful to google.
A sequel written decades later can:
reflect reality by acknowledging that decades have elapsed for the characters;
resume the narrative from a split second after the prequel ended;
leave the chronological question uncertain;
even let the narrative happen in an "eternal present."
As I remember it, Valeria was three years old in "Operation Changeling" and is a young teenager in ...Luna so maybe one decade plus has passed.