Jabra 410 and Mycroft.ai do not work out-of-the-box. I found this simple solution from github. ~/.asoundrc:

pcm.jabra {
    type hw
    card 1
    device 0
    rate 48000
}
pcm.!sysdefault {
  type asym
  playback.pcm {
    type plug
    slave.pcm "jabra"
  }
  capture.pcm {
    type plug
    slave.pcm "hw:1,0"
  }
}
pcm.!default {
  type asym
  playback.pcm {
    type plug
    slave.pcm "jabra"
  }
  capture.pcm {
    type plug
    slave.pcm "hw:1,0"
  }
}

To change the language to german I used following configuration in ~/.mycroft/mycroft.conf:

{
  ...,
  "lang": "de-de",
  "stt": {
    "module": "mycroft",
    "mycroft": {
      "lang": "de-de"
    }
  },
  "tts": {
    "module": "google",
    "google": {
      "lang": "de"
    }
  }
}