Regarding T89451 I submitted a patch which allows wikis to define their pywikibot settings dynamically: Gerrit 201446 In that the wiki could define their own sorting. We might have different types of sorting which is either a static list or also some sort of “function” (e.g. “alphabetical” or “by size”). But I don't think it's sensible to implement a function for each wiki (unless we want the users to define their sorting).

Wikis already define their sort order in a tool-agnostic manner. See https://meta.wikimedia.org/wiki/Talk:Interwiki_sorting_order#2015_usage

And pywikibot already handles most of these settings, but it needs an overhaul. We already use the auto-languagecode-fy setting for all other fy wikis, so extending this to wikibooks actually reduces the amount of complexity.

Change 288101 had a related patch set uploaded (by Aude):
Set interwiki sorting order for West Frisian Wikibooks

https://gerrit.wikimedia.org/r/288101

Change 288101 merged by jenkins-bot:
Set interwiki sorting order for West Frisian Wikibooks

https://gerrit.wikimedia.org/r/288101