Hello irena,
There are 2 ways of doing this.
1. English and German site use the same categories, but you translate the category title so it will appear in the respective language properly.
2. You create 1 set of categories for English and 1 set of categories for German. Then you create a menu item using EasyBlog All categories layout for each language. Here you set the categories to display for each menu item.
Hope this helps.
Thanks!