Nicely done , the setup looks very clean. I especially like that you have your animation setup with an alpha blend that is becomes enabled after you calibrate, I did something similar and is the correct way to support different control modes.
The only thing left to do is scaling the arm output based on user to avatar arm ratio. I also think that knowing your avatar’s shoulder midpoint (e.g. via a socket) would allow for the base offset to be calculated automatically and relative to the avatar. Will take a look at myself when I get the time.
Keep up the great work!