Hi, I’m having almost the exact same issue.
I already deleted all Sims 3 files and started from zero, and I also cleared the EA App cache. This helped in that I can now start the game and it doesn’t crash immediately when I open the launcher. However, I still receive a notification saying that the launcher has crashed.
I’m using the 64-bit version of The Sims 3 on a MacBook with macOS Tahoe (Version 26.1). The game is playable now, but the launcher instability is still there.
If anyone has found a permanent fix or knows what causes the launcher crash on macOS Tahoe, I’d really appreciate the help.