Could someone fix this by enabling both /doc and /док (and /dok, Latin translit.) function same, or somehow else? Problem is that documentation pages of modules cannot be edited; they are locked after required change of Translatewiki message defintion/translation for default English /doc.
(Unrelated to Wikimedia-Bugzilla hence removing tag (I'm curious how you chose to set that project tag? :) .)
I'm not sure why this was filed in Wikimedia Phabricator. If I understand you correctly some change (unclear what you expect, please do follow https://www.mediawiki.org/wiki/How_to_report_a_bug and provide 1) clear steps to reproduce, 2) expected outcome, and 3) actual outcome) can be done on translatewiki.net so what blocks you from performing that change on translatewiki.net ?
The current code has no way of supporting multiple suffixes. If you can settle on just one suffix, you can adjust https://sr.wikipedia.org/wiki/MediaWiki:Scribunto-doc-page-name to match.
As for that page, where the top revision is "wikitext" but MediaWiki think's it's "Scribunto", you should be able to fix it by using Special:ChangeContentModel to change it to something else (e.g. "plain text") and then back to "wikitext" or by using the API to make a (non-null) edit.
@Obsuser: If you can judge that it is "simple", please be welcome to provide a patch: https://www.mediawiki.org/wiki/How_to_become_a_MediaWiki_hacker . If not then please never assume that something is simple for somebody. Thanks!