Hi Jean,
Yes I know the FSM is big, I combined 3 different Kubold controllers into 1. I had a basic movement controller, a sword fighting movement controller and a rifle shooting movement controller. I tried to use the 3 different movements with separate FSMs, sending events, testing bools and so forth, but it caused lags in my animations. The mecanim state machine is also complex, I have close to 800 animations. It's been working great so far.
I use the Unity Hub, so I now have versions 2017 and 2019. I think I read somewhere that DoTween was the best tweening solution. I think I will try to convert to that. I will see if off link mesh works in version 2017.
Thanks,
Rick C