Complex sentence: Currently, it is not officially known why he opted out of the gigs.He was replaced onstage by Stefan Pfaffe, who is a Kling Klang employee, working for the group as a video technician.
Split into simpler sentences: Currently, it is not officially known why he opted out of the gigs. His position onstage was filled by Stefan Pfaffe, who is a Kling Klang employee, working for the group as a video technician.