HamletNDisco I would suggest posting in the master bug thread (linked above) rather than here because to my knowledge, no one from Maxis will ever see these posts. But they're asking for saves in the master thread, with instructions for how to provide them linked in the accepted solution.
It would also be helpful to provide a lastexception file, one that accompanies an error 123. Please delete the ones you have now—they're in the same Sims 4 user folder—trigger the error, find the new LE, and include that with the upload. You can copy and paste the text of the LE into a reply, or create a .rar file and attach it.
For your own troubleshooting, you can try changing the lot type of any affected lot. At least some of the problem seems to be stuck events, and changing the lot type to generic or residential, even temporarily, should clear the events. If you can't load a save, try loading a different household instead, at least long enough to change the lot type or invite the affected sims to a different lot.