The Crinfrid Reavers also appeared in the "Smok" episode of The Hexer.
The Crinfrid Reavers make an appearance in the prologue of The Witcher 2. At that point in time, they are without Boholt and have a new recruit, Newboy.
In the Blood and Wine expansion, a group of Crinfrid Reavers make an appearance during the secondary quest, Mutual of Beauclair's Wild Kingdom, where Geralt can reveal they share mutual acquaintances (namely Boholt, Kennet, Desbrut, and Newboy).
Images from the graphic novel, "Granica możliwości":