is this not also correct "for what reason have you made it" ?
I don't immediately see why not. It may depend on context.
As a British English native speaker I'd say 'what reasons have you done it for' is a more natural construction
'Why did you do it' is something much more natural, in my opinion
"What reasons did you do it for?" was not accepted although it sounds more idiomatic;
Would "Why did you do it?" be accepted?
I don't think so, that would be translation for "Perché l'hai fatto/a?".
We Italians use more sentences to say this.
Perché l'hai fatto?
Per quale ragione l'hai fatto?
Per quale motivo l'hai fatto?
You can choose your favorite
I toyed with that idea as well, but with Duolingo, it seems a literal as possible works best
I think they're equivalent.
It worked for me.