I can only answer authoritatively with respect to the Ubuntu Official documentation on help.ubuntu.com, however for Ubuntu desktop, the same stuff is also in the yelp based help package.
The Ubuntu Serverguide is published in about 64 languages, however only French Italian and Russian seem to somewhat keep up. It is published in all languages regardless of the percentage complete on the translations status, meaning some languages are basically just U.S. English. There were very late changes to the serverguide this cycle, and so translations are behind. We published what we had yesterday anyhow. We are still struggling to get subject matter expert input for several chapters which are obsolete, Samba for example. There will need to be point releases. The PDF version of the serverguide is only published in US English.
Since the serverguide is NOT a released package we not bound by any SRU (Stable release Update) rules. Also, it has been our observation, over a number of years now, at least with respect to the serverguide, that translators work on it when they feel so inclined and not to any deadline. Therefore I always offer to just to an update publish whenever asked to, rather on some fixed timeline. We have never been asked.
The desktop help documents are also published as a package and as part of the language pack, and therefore must adhere to the release schedule and SRU rules. It is published in about 66 languages, regardless of the translations percent complete. Basically, a snapshot of translations is taken at the release schedule deadline, but work can continue thereafter towards a point release. Late changes to the naming of "Ubuntu Software" from "Software" which had just changed from "Ubuntu Software Center" missed all deadlines and will have to be an SRU update, probably about the 16.04.1 date.
By the way, that link you gave for the translations status, does not include the serverguide, something that has annoyed me for years now.