alt Hacker NewsGerman here. A "Verschlimmbesserung" is something that makes one part better and another part worse. If it only makes things worse you don't need a German word for it, you can just call it worse.
For things that were intended good, but ended up bad, there's an English idiom: the path to hell is paved with good intentions.
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Both my memory (as a German) and Duden disagree with you.
> etwas in der Absicht, es zu verbessern, schlechter machen > > https://www.duden.de/rechtschreibung/verschlimmbessern
"Making somewhere worse with the intention to make it better".
My understanding is that a Verschlimmbesserung stems from a genuine intent to improve something, even though it ultimately has the opposite effect.
> For things that were intended good, but ended up bad, there's an English idiom:
Better is the enemy of good.
Old Italian proverb: "il meglio è nemico del bene"
Shakespeare, King Lear: "Striving to better, oft we mar what's well".
Yeah, no, it means wanting to make things better but ending up making them worse.
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Not a German but Duden disagrees with you [0]: "etwas in der Absicht, es zu verbessern, schlechter machen".
[0]: https://www.duden.de/rechtschreibung/verschlimmbessern