"You are an interesting woman."
Translation:Jesteś ciekawą kobietą.
I thought this would be ciekawą kobietę?
Isn't this how accusative works? Or maybe this is not accusative?
But it looks like kobieta is a direct object of verb lubić?
Yes, that's a problem that most of the sentences with "you" don't accept the formal versions although they should. But to add it everywhere would be an enormous job. Anyway, your sentence is perfectly fine, and I added the formal version here.
Pani to ciekawa kobieta was rejected . Can to be used together with the formal you?
It doesn't sound good to me. It's almost like a pronoun, in a way - and we reject the versions with a personal pronoun + 'to'.
Although I wouldn't be surprised if some other native disagreed with me now. Still, I think we'd agree that "Pani jest" would sound better.