Kobo devices can display the series information if it is in the internal database. When you buy a book from Kobo, and sync it to the device, this will be filled in. For sideloaded books, the series info has to be added in some other way. The Kobo Touch driver in calibre will do this. The driver does this when getting the list of books from the device. But, it can only do this for books already processed into the device database. Hence, when you send a new book to the device, the series info is not set until the next time you connect.
The series info is displayed in the library lists and a search will find it. But, there is no way, except a shelf, to group the books together or in order. If you want to sort the books in a series together, then you still need to use a plugboard like that.