Stuff like the post you are replying to is common "good luck with insurance" trope. Insurance protects you from stupidity, errors, and negligence. It doesn't protect you from fraud or intentional malice, but using an uncertified device is not fraud.

Note that after an accident related to personal stupidity or error, an insurance company could decide you are too risky to further insure, or that the cost for your insurance should increase dramatically. But they can't deny a claim.

All of this is of course a significant summary, but insurance won't (can't?) deny a claim linked to an uncertified electrical device in normal circumstances.