It looks nice! I like the tab feature within pages.
Is there also a harmonica/expansion feature of some kind? If a user is in an install flow then linking to other pages and forum posts takes them out of the flow, which is confusing. It would be much less confusing to be able to keep them on the page but offer an explanation in an expanding section on a click on a certain link.
Usable backup is crucial (core)
And I very much agree with all of the comments of @TheNomad11 in the above. I perceive usable backup guidance/solutions as the last frontier for usability of Yunohost. I have not dared using my Yunohost instance beyond TinyRSS basically. When I currently answer the question “Why you no host (documents and other files)?” the only reason left is: “Because I’m scared I will lose days or much more of writing/editing work by server failure/theft/fire/hacking”. To get a Yunohost server production-ready for storing and editing files, music etc. etc. a usable and reliable backup solution is most important. Otherwise users are taking great risk in loosing lots of work in case of failure. Some important features of this backup feature I can imagine to be general user-centric design, and more specifically: automated, remote/local, encrypted, incremental, verified, easy restoring.
In fact, usable backup and restore is so core to administering a server that we should strive to implement a usable backup feature within Yunohost admin itself. Instead of relying on other apps. That is because we don’t have much influence on the other apps and they often lack good usability or maintenance. Good documentation is a good first step to get a grip, but in the end, all crucial functionality should be usably offered within Yunohost - or less preferably: in highly usable documentation walk-throughs.