https://www.superiorthreads.com/medi...guide-home.pdf
This is the best reference for Superior threads especially, but even a great starting point for most thread / needle / tension combinations.
I'm not familiar with the Janome, which way is the bobbin oriented? Horizontally or Vertically? Horizontal (according to SM shop I talked with) requires higher tension for FMQ than the Vertical, but it shouldn't be astronomically higher... it should be possible to balance the tensions. 98.9% of my FMQ to date has been on vertical bobbins