The Vikings, the Moors, the Rusyns and the Byzantines invaded the HRE. Beat them to save the Holy Empire!
https://www.warlight.net/SinglePlayer/Level?ID=883812

I still cant beat it but maybe you can proof that it is beatable. Or if it is too hard Im curious about your opinion how should I ease the difficulty.

You can vote of 3 easing:
- give a commander to HRE
- give cards to HRE
- give extra income for "Holy Roman Empire" bonus