just an update: The ERC seems to have never left the wallet. After waiting for days for it to arrive on Crex24, i "deleted" the wallet in Coinomi and re-added it. My ERC were still there - without any sign of an attempted transaction.

A few weeks later i tried to transfer a little amount of fresh ERC from Crex24 to the Coinomi-wallet. I am waiting again, now 

Later i noticed, both Coinomi wallets on my phone and the windows-pc are stuck at block height 467.723, although we are a few thousand blocks further now. There are resync-buttons in the apps, but they don't do much. I will give another update, when i hear from Coinomi support about that stuck blockchain syncing.

Would appreciate to hear from other Coinomi users with similar experience.

And: i installed Europecoin Core for Windows - but didn't find an option to import my keys. That's why i am stuck with Coinomi rn.