Unfortunately, it’s not public yet.
It must be some CSS issue, as there are no Javascript errors related to it. I did find an old post that changed the fontsizer code, allowing more flexibility on the translation side, as most of it is hardcoded in the JS.
The site also has an alternate CSS, and part of it is copied from the theme being used, but much smaller. However, it works on the admin and not on the journal, which bugs me a lot.
Not too easy to fix, and I have little time to spend on this, so I ended up creating my own fontsizer plugin, with a different code, from the working example I posted (not the copied code, as it has some issues, missing commas, etc.).
It’s also easier to maintain on future upgrades and patches…