Why not just convert the .hlp file to PDF? There are a number of tools to do so, but I don't know of any free ones.
I too have been frustrated by this Winhlp32.exe stub, since it first affected me in Windows 8. Microsoft has as little interest in old MS and 3rd party applications that use the legacy Windows 32 help system as it has in Windows XP, to the extent that thy receive no revenue from these legacy programs. Whereas the kind thing to do would be to offer an on-the-fly conversion of the legacy .hlp file to an acceptable modern format such as .chm, Microsoft has again chosen a lazy and arrogant approach to users - in effect telling users to purchase new software.
However, the official reason why the old Windows help system is not readily available is because it is inherently insecure. Any .hlp file can be crafted to do nasty things to your PC because these .hlp files can run programs, macros and other scripts.
I have read that the Microsoft Installer for Windows 8 winhlp32 only works on US-EN systems (you can change this temporarily to install the KB update), but subsequent recent updates in Windows 8/8.1 have broken the functionality of winhlp32.exe. As well as this, the component store may replace the functional, older XP version of winhlp32.exe, with the stored 10KB useless stub, with the up to date timestamp.
Am I right in thinking that the update mentioned in Post1 (https://support.microsoft.com/en-us/kb/917607) fixed the problem for Windows 8.1, until update KB3000850 came along and broke it?
But KB917607 isn't offered in a variant for Windows 10 at all?
Although it doesn't solve the problem immediately, I think it wouldn't do any harm if people 'upvote' the posts in the Feedback app which ask for windows help to be reinstated.
Feedback - Send to Microsoft in Windows 10 - Windows 10 Forums
This lack of support for Winhlp32.exe OOTB has been present in every Windows consumer version since Vista, and (grudgingly, it seems) each time, a "fix" has been made available, usually by optional updates that are not offered by the routine update systems.
Then, if the installation can actually be made to work (often it fails with "not applicable for your system" or similar error), many features of Windows Help can only be made to work as intended with registry edits, further Microsoft "Fix It" patches, or not at all due to security features in the OS, or just undocumented error messages.
Why, oh why, does not Microsoft cut their losses and provide a hlpwin32 conversion script that decompiles the legacy help files to their RTF source files and indexes, and then recompiles these to CHM help format, and offer support for difficulties with this process, rather than swimming against the tide of users who wish to continue to use their legacy software, often bought at great expense at a time when software was not dumbed down to the status of "app"?
Following are basically same as those of "Title: From the technical viewpoint, is the information by M$ enough good?" written by me. But the understanding might be easier because of having many pictures. Therefore, this is just information for you and users.
By the way, regarding a tool to fix some problem(s), it might NOT be a good idea to use some tool (e.g. "Fix It”), which contents cannot be checked by users, even if M$ (company) recommending it to use.