That is strange. I tested using the same version on my side, and didn’t experience a crash any more.
Trying an earlier Steam Audio version is definitely worth a try.
Thanks for the additional details! I was able to reproduce the “sound stuck on the left” issue as well.
I have discussed this internally with the dev team, and since the Steam Audio Spatializer is a third-party plugin, we unfortunately have no control over the code. Any bugs inside the spatializer would need to be reported directly to Valve.