Controllability vs. Stability in PHAK. Is it an error?
Your understanding of controllability and stability is correct, for the following definitions:


Controllability: the response of an aircraft in steady flight, on pilot control inputs. For instance deflecting the ailerons: a high resulting roll rate means a fast response.
Stability: the tendency of an aircraft air frame to return to trimmed position after a disturbance in air stream. Note that in this definition of stability, the airframe itself does all the work in getting back to neutral position, no pilot input required.


So the above is for steady, trimmed flight. The paragraph that you cite is about how to provide flight control inputs to recover from a spin. Now we need both control deflections and aerodynamic stability to recover. If the CoG is too far aft, there is not enough stability and the airframe may not recover even if the correct control inputs are given.

Use of the word Controllability is correct here, since it refers to controllability of recovery from a spin.