I looked back on your other threads, and I think I might have given you some bad advice above here – looking at your STER data shows me that your desired and actual turn rates match very closely in both logs. Don’t change your P and FF values yet.
Seeing the desired lateral acceleration osciallate means that the navigation controller is the one that is causing oscillations now. Your L1 settings -
Probably need to be tested and optimized. Try increasing the period and decreasing the damping slightly. If I remember correctly, we had you increase your TURN_MAX_G from previous missions so that you could turn sharply on corners. Unfortunately that probably allowed the navigation controller more authority during straight runs - and now its settings are causing some oscillations.