No, you are confusing this with the traditional GCI/JER charter flight which is scheduled to be operated by an ATR (LH5020) and starts on Apr 24.
The equipment change relates to the new seasonal scheduled flight by Lufthansa (LH4938) that starts on Jun 21. Originally it was also to be operated by a Contactair ATR72, but now pops up as an Eurowings (ex Duo) CRJ700.