I asked on Janome's facebook page and they said to keep magnets away. I asked both on the page and in a message to them and they replied to both. I'll keep doing what I'm doing.
their PM to me:
We strongly recommend that you keep magnets away from computerized sewing machines. Over time magnets have been known to cause the machine to stop functioning.
the question on their fb page:
https://www.facebook.com/JanomeSewin...52467003673223