I'm trying report an issue as well. For my experience there is no internal report bug process.
I got a hanging issue that obvious a firmware issue. I've sent several email to them with a video link but no single reply, instead they ask me to bring my camera to their repair office. They tested my camera with no issue ( with their internal test device i guess). Then they downgrade my firmware with hope that it'll fix the issue. I ask them if i found that previous firmware fix my issue, will they report to fuji to fix the firmware. They said no, just that's it.
So if you have firmware issue, ask them to downgrade it for you, don't do it yourself by their advice or sit tight and finger cross that they will found the issue themselves cause they wont listen you anyway.