Very hard goat cheese exists and is called "séchon" (from "sécher", i.e. to dry out).

And yes, camembert du buffala is produced and exported. Can't blame the author of the website for not knowing that, I think it is a very recent invention* and in a very minor volume compared to mozzarella of the same milk.

*I couldn't find a source in French or English, and my Italian is not good enough.