I have an issue with Japanese (and other Asiatic language like Chinese etc...), the TOC has not well formatted characters. After a lots of debugging I found that the whtdat*.js are corrupted characters.
Altought I selected the Encoding "Japanese" in the WebHelp interfece, the whtdat*.js are produced in UTF-8 format and so they are illegibile.
What I have to do to see the right characters in the TOC section for Asiatic Languages?
I think this is one that only Adobe can fix.
You could try firstname.lastname@example.org to see if they are aware of it and have a fix.
Otherwise please follow this link to report bugs. https://tracker.adobe.com
Post the link to your bug report in this thread and others can vote for it. The more people who do so, the higher it gets prioritised.
In case someone else can think of something, you haven't said which version of RoboHelp you are using. If 2019 is it Classic or the New UI?
I'm using Robohelp 2017.
You could check that the project settings are set to Japanese. And maybe the operating system language (although I thought that was only necessary with chm files).
Otherwise, you could create a small test project and see if it works there. That would help rule out a problem with your current project.