Yes. Ketron Germany published a german manual. The manual shows how to configure SongBook+ and Ketron keyboards to automatically open a registration on the keyboard when a song on SongBook+ is opened and also to open a song in SongBook+ when a registration on the keyboard is selected:
German manual download from here: Anleitung_AUDYA_Songbook.pdf
English translation see attachment.
Attention!
The manual is a bit outdated and contains screenshots of an old version of SongBook+.
An important difference to the current version of SongBook+ is, that the settings of SongBook+ are now contained in the app itself (see button with gear wheel icon) and no longer in the general "Settings" app of the iPad.
The manual also says that you need an iPad 1, 2 or 3. In the mean time the current version of SongBook+ needs newer iPad models. See here for more information: https://baumsoftware.freshdesk.com/a/solutions/articles/17000062939