Do note that nodebb is a forum platform, not a CMS. I've seen some awful attempts at trying to shovel a CMS into a forum platform in my time. SMF springs to mind.

You'd probably have to write an SSO plugin to share authentication. @julian has a ton of SSO plugins that you could use as a sample in writing your own one https://github.com/julianlam?tab=repositories As far as user management... somebody was asking for a WP user management plugin. Kind of like if you upgrade a user's privileges in WP, it updates it in NodeBB as well. It's doable but the client didn't end up going for it so we never ended up building it

Here sir, take my vote.

Someone's tried it before: http://www.nutritionask.com/ With a bunch of widgets, changes in the design. And now you can sort by upvotes too so it's probably much more possible to do a Q&A style site than it was a month ago when you first asked

@julian The problem is not here. I see the page but I want to change its template. To explain more : I create a custom page /accueil with the custom-pages plugin which seems to auto-generate accueil.tpl. I cannot change accueil.tpl without changing this custom-pages module (?). No success playing in my own theme or from another plugin. I will also need to change the onlineusers.tpl template from widget-essentials and I think I will have the same problem (?).