I have problems with this functionality.
Editing in French was a bit tricky because the mouse cursor didn’t let me chose a category. I used the keyboard to choose a category then. I had no problem with German and English.
The main problem is that the selection doesn’t work. I chose one category (for example travel). Then the “My level” shelve is shown. If I switch to “My Picks” I saw the same lesson a lot of times!
I think a lot of people don’t understand what they could do there. The functionality is nice but not obvious.
And I admit that I miss the category as a choice on the main page of the library. For me this is more interesting than the provider, but this is my personal point of view.