Hello!
Regarding name "
Ana", you wrote that Croatian version is "
Nensi" which is so uncommon (like a Japanese name in
Europe for example), and it is phonetic form of the English name "
Nancy", so I think the information is irrelevant at best and possibly wrong.
However, most Serbian variations of names you listed (
Ana,
Jana...) are common in Croatia also, and I dare to say that "
Jana" is even more common in Croatia then Serbia (regarding the classic literature).
And I would also like to make an addition: "Ančica" (pronounced An-chee-tza) is also common form of the name
Ana in Croatia.