I'd post your computer specs as well. Fellow mac user here, my game has mostly been running, but with a couple of graphics bugs. I also ran into a problem with it not starting when I tried to turn VSync on and I had to delete my graphics settings file to fix it, but it sounds a bit different from yours.
Also, I subscribe to ShadowPC which (if you have good internet) lets you stream a custom PC where you can download all the games that have issues on Mac. If you can't find a workaround for this version of Baldur's Gate on your mac, you can pay about $15 a month to use your mac to stream a beefier PC.
