I do think Zagreb is brilliant
I am sorry but i do not know what you mean by cases or the other one (!), i was taught Croatian at a young age, my mother spoke to me in it, so i grew up bi-lingual, but if you asked me to write an essay in Croatian i wouldnt get very far. I can spell and write and everything but really i need to go to a Croatian school, or do what my father did in Zagreb. He learnt the language at a School of foreign languages in Zagreb, and he got money by doing Engish classes there.