I typed in "noví dům" and got it correct. So does this mean "nový" and "noví" can be written interchangeably?
No, it is wrong.
Did it say that it is correct or that you have a typo? A screenshot would be helpful.
I'm certain that it just said I was correct. If it happens again I'll take a screenshot for you.
The same happened to me. It told me nový was correct
Nový IS correct, there is no question about that. Or what exactly did you answer and what exactly did it tell you?
Where is an article?