I have noticed that the master HOWTO page of the website
Lists a few select howtos, but by no means all.
There seems to be no direct way to list all the HOWTOs available. Maybe the master HOWTO page should be automatically updated from the /howto/ content list?
In the mean time before an automatic update you can create a new topic on this site and and all of the links.
I don’t know how to find the all the HOWTOs available that you are referring; I do know how to use the SWI-Prolog search. Is this what you are implying?