This is why electrical work is one of the few things I am relatively comfortable “overpaying” for, as I’ve seen some really, really shoddy work. My installers, who knew what they were doing, and who worked directly with Lucid before the EVSE was even released, originally installed it on chair lugs and Lucid made them change it to compression lugs, as per the manual. My guess is your guys used chair lugs, or similar, and thus did not follow the spec. That’s on them, unfortunately.
Based on my experience with that, I’d guess the compression lugs are important.
I’m so glad to hear everyone is okay and it wasn’t worse.