Tinsori Light and Jen Sin yos'Phelium are mentioned in Scout's Progress, preface to chapter 29.
Years later the authors decided to use Jen Sin and Tinsori Light as more than just a chapter header. Thus, the short story, The Space at Tinsori Light. It's chilling, obscure, and fascinating, with Artifical Intelligence and flashbacks to the old universe and The Great Enemy. 
In the short story, Jen Sin yos'Phelium, former Scout, and the best pilot in Clan Korval's roster, accidentally wound up at Tinsori Light while escaping enemies. He was badly wounded, his ship unable to jump again without repair.
Excerpt, The Space at Tinsori Light: "Any ship arriving here was a ship in need. The operator extended her hand and touched a plate set away from all the toggles, buttons, and tags that attended to her part of the function. She touched the plate. And woke the light."
More years pass, perhaps centuries. Then Quin yos'Phelium includes Timsori Light in his list of escape coordinates, in Roving Gambler (short story).
Excerpt, Roving Gambler: "The coords got mentally filed away in order, Lytaxin, Springwood, Tinsori Light. Well, that last one, that was one he'd been supposed to forget, to put out of his head as a last resort just ahead of, or maybe behind, Jumping into a sun. He'd not have had it at all except for the oddity of his grandmother knowing it, though she was not now and never had been a pilot. "
The origin of the Tinsori Light is described in The Gathering Edge, chapter 22.