I was wondering if you are able to legally per the games ToS use proton/wine to play everquest on linux?
It's not virtualizing Windows, so it's not against EUL in that regard. It's also not a supported OS/configuration so you are on your own for configuration/issues/support. To date (grain of salt), doesn't seem like there have been suspensions from those who have mentioned having used WINE, but YMMV.