Hi!
Ana and Jana are marked as Croatian names.
Regarding Nensi, I wonder if it is as rare as you think.
https://actacroatica.com/en/name/Nensi/ - This Croatian website describes it as "one of the quite common names (among the top thousand)"
https://forebears.io/x/forenames/nensi - Shows it as the #774 most common name overall (both men and women)
Searches restricted to Croatia on social media show many bearers.
There are no Wikipedia articles devoted solely to a Nensi, but there are Croatian people named Nensi mentioned in other articles:
https://en.wikipedia.org/wiki/Croatia_in_the_Junior_Eurovision_Song_Contest_2005https://en.wikipedia.org/wiki/Milena_%C5%BDic-Fuchshttps://en.wikipedia.org/wiki/Ivo_Grbi%C4%87_(artist)https://en.wikipedia.org/wiki/Ivan_Zajc_Croatian_National_Theatreetc.
This is why I'm hesitant to mark the name as rare.