HANA in Czech or Slovak isn't only a "short form of Johana", it is also a form of the name Anna, in English Ann, but Anna is maybe one from Slavic form of Hannah, Hana @ Anna, Johana is Jane.
While I lived in the Czech Republic, one of my best friends was named Hana. The name's always been positive to me, but I do prefer it with two 'n's (and probably an 'h', too).
One of the main characters in The English Patient by Michael Ondaatje is named Hana - she is a young French Canadian nurse working in Northern Italy during WWII.