The Star Charts book placed Risa at Epsilon Ceti due to the frankly poor assumption that NX-01 started her first-season adventures from Earth - even though "Broken Bow" is pretty explicit in that the adventures began from the Klingon star system instead, a system that later in the show is revealed to have been the "capital system" Qo'noS.
Supposedly, Archer's adventures took him at least 130 ly from Earth during the first two seasons ("Dead Stop"), leaving a wealth of options for the location of Risa (but suggesting that Romulans lay those 130 ly from Earth, since "Dead Stop" is a sequel to "Minefield"). Yet Archer wasn't trying to get as far out as possible, or at least he never indicated such a mission goal. Rather, he might have well been zigzagging in the unexplored volume of space between Earth and Qo'noS for much of that time, making Epsilon Ceti or some other "southeasternly" star a good candidate for Risa.
Let's remember that the ship rather effortlessly spanned the 50 ly from Earth to the Delphic Expanse in just seven weeks. She could have gone much farther than 130 ly if she really wanted during the first two seasons. Still, the visit to Risa comes just two episodes before that 130 ly reference, in the middle of episodes that indicate our heroes are within the zones of influence of both Vulcans and Klingons. Some Cetus star might thus be all right for our purposes, but Epsilon Ceti is actually a bit too close...
Timo Saloniemi