Sims 3 64-bit crashes immediately after pressing Play on Launcher

Prompted by the release of the 64-bit version of Sims 3 for Mac and the current EP sale on Origin, I purchased the game (Sims 3 Starter Pack). Unfortunately, I can't get the 64-bit version of the game to run at all on either of my 2 machines.

Both are still on Mojave (fully patched including all security updates) due to 32-bit software I've not been able to replace yet. Neither had ever had either Origin or a previous version of The Sims 3 installed on them prior to this, so (in theory) there should be nothing to conflict with the game.

Symptoms:
* Origin launches and connects OK
* The Sims 3 (64-bit & Metal) selected, then PLAY
* Sims 3 Launcher comes up okay, version shown is 1.70.305
* I press PLAY, and it immediately crashes with "The Sims 3 quit unexpectedly"

Crash is always:

Exception Type: EXC_CRASH (SIGABRT)
Exception Codes: 0x0000000000000000, 0x0000000000000000
Exception Note: EXC_CORPSE_NOTIFY

and from the thread:

Error Code: 0x02000148
Trap Number: 133

When run in full screen mode, I see some flickering as the game tries to change resolution, followed by a black screen, and then the crash report popup - by which time the launcher has disappeared and Origin has popped back up.

I edited Options.ini to change fullscreen=0, and when launched that way I see the launcher plumbob disappear from the dock, a new plumbob appear and bounce exactly once, and then the crash report and Origin pop up. It's unclear if that single bounce is the launcher or the game, since both have the same description.

Last played always says "Not played recently", because the game never gets far enough to register. It never makes it as far as displaying the EA, Maxis or Sims 3 logos, let alone the loading screen.

This is consistent on both machines. Both are Metal capable - one a 2017 27" iMac and one a 2013 Macbook Air - I wouldn't plan to run the game on that, it was installed purely for comparison test purposes.

I have tried the following without success:

* Checked Origin for updates (none)
* Checked the game for updates (none), then ran a repair on it
* Editing Options.ini to try to change all graphics options to low
* Editing GraphicsCards.sgr and GraphicsRules.sgr to add the details of my graphics card to the database (after which they were reported correctly in DeviceConfig.log with [Found: 1, Matched: 1])
* Uninstalled the game (originally installed with the Late Night EP and Loft SP from the Starter Pack), and reinstalled with just the base game, in case of EP/SP incompatibilities
* Deleted Electronic Arts/The Sims 3 from my Documents folder and allowed the game to recreate it
* Contacted EA Support, who weren't able to help but did have me run through the process of resetting Origin, and redownloading and reinstalling it

They then suggested that I try here.

I'm at a loss for how to proceed. I did clear down the 64-bit version of the game entirely on one machine and install the 32-bit version instead, just to confirm that the problem was with the 64-bit version and not my machine. I ran a couple of fairly long sessions on that over the weekend, and it ran just fine. But if I'd wanted to run the memory limited non native 32-bit version of the game I could have bought it in 2009. It was specifically the 64-bit version of the game that tempted me, in spite of its known issues.

Ah well. Any help or suggestions that anyone here can give will be most gratefully received. I may be a newbie with Sims 3, but I've done a lot of poking around in Sims 2 over the years, so I'm happy to try any tweaks or edits that might help.

Spec of the two affected machines is as follows:

iMac:

macOS Mojave
Version 10.14.6
iMac (Retina 5K, 27-inch, 2017)
Processor: 3.8 GHz Intel Core i5
Memory: 24 GB 2400 HMz DDR4
Graphics: Radeon Pro 580 8 GB

MacBook Air:

macOS Mojave
Version 10.14.6
MacBook Air
Processor 1.7 GHz Intel Core i7
Memory: 8 GB 1600 MHz DDR3
Graphics: Intel HD Graphics 5000 1536 MB

Thanks!