Animenz arrangement of Tokyo Ghoul theme, is very complex and hard. Theishter arrangement it's not 'very' hard, it would be a 9-10 grade.
You asked for what grade would that piece be : There are many versions, but those 2 are the most famous and complete. Well, Tokyo Ghoul is a very famous 'anime' ( show ) which it's opening theme was arranged for piano by Theishter and Animenz. They are not composers, they are arrangers who arranges music from different shows called 'Anime'. I have always loved classic music, but I've been also attracted to what you call 'Animenz' and 'Theishter' music. Im not a piano teacher, I'm an advanced piano student ( actually this is my last year in the conservatory of music I have been studying & playing in the conservatory for ten years now). Well I dont know if you'll find this useful since I'm replying a month later haha a bit late, but anyway im gonna answer this :p
