If you smoke in bed and fall asleep and burn your house down due to negligence the insurance company still covers you.I would strongly advise not doing this. You will have many here tell you it is just fine and that the internal components can handle it, but no one considers the risks. What if something goes wrong and it burns your garage down? Even if no life is at risk, and even if the EVSE isn’t technically at fault, if the insurance company finds out you were using 240v on a unit only rated for 120v they will in all likelihood deny your claim and you will have to pay for a new garage (or even just the car itself...) out of pocket. It really is best to spend the few hundred dollars on a decent portable EVSE and be done with it.
If you fuel up your lawn mower in the garage with the engine running, spill gas all over and burn down your house through negligence, the insurance company still covers you.
If you blah blah blah and blah blah blah happens due to negligence the insurance company still covers you.
If you INTENTIONALLY burn down your house, this is called arson, the insurance company does NOT cover you and you face legal penalties.
The stock EVSE being used on 240V is ZERO risk, so it doesn't even fall into this category. If you fail to label the adapter and someone plugs in a 120V device that is the only danger and it can be mitigated with labels and ELIMINATED with locking devices.
I am sick to death of fear mongering and misinformation about this subject.