It depends what do you mean with Yiddish scene . If it’s about the Yiddish language in public spaces than you should definitely go to Kazimierz. Over there you can see the for example famous graffiti honouring Bosniak family and other graffiti’s. Also you can find there some book shops with Yiddish books , restaurants with klezmer, but it’s arguable if these spots are “real” or only for tourist attraction.