In Jack v8.0 the real-time Fatigue tool was moved into the Task Simulation Builder (TSB). We will correct the outdated information in the Task Analysis Toolkit Manual - thank you for pointing that out!
From v8.0 Release Notes:
The real-time fatigue and recovery tool has been re-worked and integrated with TSB. It offers an estimate of the fatigue accumulation and recovery experienced by a figure over the course of a simulation. Based on the Rohmert fatigue equations, the tool calculates the joint by joint strain experienced by the figure throughout the simulation, and compares this with the total recovery time available. The final report indicates if the task sequence is likely to cause an accumulation of fatigue and offers guidance on corrective actions.