I'm also struggling with the game which is a huge shame, as I love binge-playing it from time to time. I have been playing it since 2013 on the same MacBook Air, and it has always fuctioned well, though not with the highest graphics settings.
Currently running High Sierra 10.13.3.
I sincerely hope there will be an update, a patch or whatever, so we can continue to build and enjoy SimCity!
Also, WHY do EA continue to sell the game and expansions in Origin, when they obviously don't work?!