Hi! Linux noob, but I’m also a linux gamer.
I found someone on TF2’s proton page who had the same audio issue, apparently enabling -nojoy should fix it. About the graphical issues though, it might be related to the AMD drivers which I’ve heard cause a lot of problems for a lot of people on linux gaming. My best suggestion would probably be switching it out for something else (?) (really not helpful I know).
Other than those, my final recommendation would be leaving a report on protons TF2 page (which only has a bronze rating at the moment). Hopefully that provides anything you didn’t already know.