IWR6843: How to assure the output of tracker and point cloud correspond to same frame

Hello champion,
     I am looking at 68xx overhead people counting demo in C:\ti\mmwave_industrial_toolbox_4_1_\labs\people_counting\68xx_overhead_people_counting.
     I have a question below:

1. MSS got the point cloud in task MmwDemo_mboxReadTask (pri = 4)
2. Then, MSS post semaphore  gMmwMssMCB.appSemHandle to trigger task MmwDemo_appTask (pri = 2) to do group tracking.
   
3. MSS  in task MmwDemo_mboxReadTask call UART_write to output point cloud, tracker output and index
   

Since the priority of MmwDemo_mboxReadTask is higher than MmwDemo_appTask, how to make sure in step 3, the tracker output correspond to current frame (in my opinion, step 2 can't be run before step 3 complete)?

Thanks,
Adam