Maybe...the project (right or wrong) used to fall under java ee code base from what I can tell (1) which has since been archived, assumedly because it transitioned here with no plan for Oracle to support it directly.
From a high level, the Java Help documentation (2) indicates
"JavaHelpTM is an online help system specifically tailored to the Java platform. JavaHelp consists of a fully featured, highly extensible specification and an implementation of that specification written entirely in the Java language.
JavaHelp enables Java developers to provide online help for:
• Applications (both network and stand-alone)
• Server based applications
• Applets
• JavaBean components
• Desktops
• HTML pages
So except for maybe the "Applet" side of things (which is deprecated/removed in more recent Java), it still seems potentially viable.
I can see how this is one of those grey areas where it could be usable in desktop or online (enterprise) context, kind of like say CDI where it started in enterprise and found favor for use external to enterprise usage..