Many of these terms originate during the Nazi regime and thus aren't used lightly in Germany anymore.

Other example includes: Endgegner (final boss) or Endlösung (final solution)

I would suggest to avoid such terms.

> Endgegner

I did not know about this, thanks for die Vorwarnung. In context, I'd assume "ultimate enemy" (Gegner=opponent) as "final boss" sounds videogame.

Many did in the golden age of German research, then to be destroyed by those mentioned.

Either the philosophers or the mathematicians/physicists likely coined them.

Certainly, so we have to critically look at the terms and check which have been used by the Nazis to promote their ideology. It is a call to make in each case.

Wunderkind and Endgegner are used lightly in Germany.

The parallels to Nazi Germany's striking but impractical weapons seemed intended every time I heard or read Wunderwaffe in English.

Wunderkind predates the Nazis so it doesn't have that much baggage.

Endgegner originates from Endlösung and while it indeed often is used without thought, the question if it should be used lightly.

You stated Endgegner was not used lightly in Germany when it was. You seemed to think Wunderwaffe was used lightly in English when it was not. And searching for Endgegner and Endlösung found our comments and a few opinions they sound similar. No evidence or claims of origin. I conclude Endgegner does not originate from Endlösung probably.