Meanwhile the link has changed to https://www.seti-germany.de/wiki/Challenge-Übersicht — or maybe better: https://www.seti-germany.de/boinc_pentathlon/May
5/5 - 5/19 - SETI.Germany's BOINC Pentathlon - https://www.seti-germany.de/wiki/Challenge-Übersicht_kommendes_Jahr
8/15 - 8/29 - SETI@Home Wow!-Event https://www.seti-germany.de/Wow/August
11/16 - 11/23 - 15th WCG Birthday Challenge https://www.seti-germany.de/wcg/November