The scheduled charging on the Juicebox works great with some cars, providing it is connected to the Internet, but not the Lucid. I had the issue too of the Lucid not waking up to charge and the app generating repeated error messages. But if the Juicebox is not connected to wi-fi, it becomes a "dumb" charger. Mine got disconnected when we put in new routers and it was such a pain to reconnect it, that I didn't. So now, I can either plug it in and charge immediately or use the Scheduled Charging in the Lucid, which works great. I can plug in at any time and it starts charging at midnight without a problem.
I'm not sure what you mean by charging multiple EVs. You can only charge one car at a time, so you'd have to unplug one to charge the other. Are you trying to schedule two separate charging periods on the charger? I'm not sure that they work like that. I don't think the Juicebox does.