To put it straight: In Yiddish letters as shown in Zemerl the word must be read: Dana.
It is written with a kames (long a) in the first syllable, and this sound is pronounced o in Ashkenazi or Eastern/German Yiddish. Original o (holem) would be pronounced oy (e.g. Shelomo = Shloyme = Salomon).
About Sephardic or Western/Spanish Jewish I can't say anything. As a German Orientalist I was only concerned with Ashkenazi (not my department, just out of interest), since in my region where a lot of Jews were living since medieval times my local dialect is enriched by a lot of Yiddish words still in use.
Forget the spanish influences; there is no Donna = Lady in Ashkenazi. The idea of Adonay also is invalid; God in everyday speech is referred to as Shem = The Name (e.g. Bórech Hóshem = barúkh hash-shém = praised be The Name = Praised be God).

Wilfried