Shouldn't "California state is expensive but pretty" be also correct?
That sounds unnatural in English. The only real way to say the above sentence is the way they put it.
Additionally, one can omit “the state of”—there is enough disambiguation that the proper name itself refers to the U.S. state.
Though, for consistency with the original sentence, the answer that Duolingo provides is the best translation.
It is not possible to type the dagger alif in لٰكِنّ on a standard keyboard and the answer is not accepted without it. Please fix this.
Why the translation "State of California is expensive but pretty" is not accepted.