The docs say backlinks are sorted by titles ( https://www.mediawiki.org/wiki/API:Backlinks .... "Ordered by linking page title"). I noticed that this is partially true. So while most of them look like sorted alphabetically, usually there are sections at the end of the list when there are plenty items that are not. So they look like they added later not obeying the sorting rule. The example is the article https://en.wikipedia.org/wiki/Teleology where the first page of "What links here" ( non-redirect articles) contains non-ordered items. Is this expected?
But apart from figuring out whether there's a bug or not, another thought is that the alphabetical sort (if it works) is controversial since in any form of presentation, A-items are prime visible entities, while Z-items tend to be obscured if the list is long. So is it possible to implement other kind of sort, for example, something like PageRank for backlinks, so the links are sorted by the number of links coming to them? Sure There is a technical side (whether the structure of the database will allow this) and probably legal (I hope Larry Page won't mind and won't sue WikiMedia for this)
I consider backlinks important because they tend to have "see also" and "category" flavor in them, so just by looking at a partial list, I acquire additional knowledge and expectancy.
Thanks,
Max