Issue with german umlaut Ü in case of active emoticons-addon
you can see the bug on your demo page:
If you type a german Ü this character will be transformed to a : (on the keydown event).
Thank you for letting us know. We'll check the issue and back to you asap.
The issue will be fixed once the Quill editor release a new version. This is not the wpDiscuz issue it's a Quill editor issue.