Sims 3 unexpected quitting on Mac

@Supremastyx  Thanks for the DeviceConfig, which confirms your hardware and that you're using what are probably the correct graphics settings.  I would suggest trying to play in Sunset Valley rather than Starlight Shores, at least for comparison's sake.  The latter world isn't broken per se, but SV is more stable for a few reasons, and it would be useful to know whether the crashing is due to the game itself or something more granular.

When testing, please restart your computer immediately beforehand, and don't open anything other than Sims 3 and Origin.  Your Mac has enough RAM for both and the OS and for the graphics chip to borrow from, but there's not a whole lot left over after that.

Sims 3 runs fine in Mojave, so that's not a problem.

@puzzlezaddict Hello, thank you for your answer. 

I tried playing a new game in Sunset Valley after restarting the computer with nothing else like you said. I could play for 45 minutes, travelling in World Adventures and then it crashed again and now I am not able to play anymore than 2 minutes into the game, the unexpected quitting happens all the time. My last save is in Egypt so every time I start, I am there and this is where it crashes. 

I really don't know what to do if all the settings are good. 

Do you have any other way to know where it can come from ? 

@Supremastyx  There's no particular reason I know of that traveling, or rather playing in a travel world, should cause these issues.  But perhaps it's worth installing a few mods, if you're willing.  I'd suggest NRaas ErrorTrap, Overwatch, MasterController, Traveler, and Register, all described here:

https://answers.ea.com/t5/Technical-Issues-PC/Sims-3-Common-Game-Fixing-Mods-Hero-Approved/m-p/9838855#M244208

MC doesn't do anything on its own and is part of this list for a few convenient commands you could use; the other mods do their work automatically, without need for user input.  Register in particular can help by fixing role assignments, which seem to break sometimes with WA worlds.  But the others are important too: ET and OW for general data cleanup and corruption prevention, Traveler for fixing the travel transition and some issues related to playing in a WA world.

It's also worth trying to load the backup copy of this save, especially if it's from before your sims traveled and simply adding the above mods doesn't help.  The game keeps the data from the second-to-last time you saved even if you never make a manual backup.  Inside Documents > Electronic Arts > The Sims 3 > Saves will be a folder with your save name plus another with the same name and a .backup extension.  Rename this second save and delete the .backup, and it'll be available to load at the Main Menu.

I installed all the mods you listed and loaded the backup save like you said.

The game works well in Sunset Valley and I have no problem playing but I went back to Egypt, started doing things and 2 minutes later, unexpected quit !!!  

Looks like it only coming from travelling and I hate it because it's what I love the most. I really don't know what to do at this point. 

@Supremastyx  Please try traveling to France and China as well, even if you don't want to play forward like that.  I'd like to know whether the current problem, i.e. with mods installed, is limited to Egypt or more broadly related to traveling.

It's also worth saving as soon as your sim arrives in the new world, as in, when the arrival action (a suitcase in the action queue) disappears, then quitting and reloading.  While The 64-bit Mac version of Sims 3 doesn't have the same RAM limitation as its 32-bit counterparts, traveling is still hard on the game engine, and quitting and reloading clears a lot of data that the game can hold onto unnecessarily.