Hi @Aklapper, sorry for not following the correct procedure – I did skim through those pages first, but apparently not thoroughly enough (since I missed the fact that tags ought to be discussed first).

I did discuss the idea with @Lydia_Pintscher and some others on Telegram before creating, but unfortunately not here in Phabricator. The idea is mainly to replace T144272, which was getting quite unwieldy for those of us who need to check (and follow up on) its subtasks, and also used for more than what was its original purpose (hence the different columns in the tag workboard). I have already added the tag to all of those subtasks, plus the ones I found that were relevant in I18n. I'll go through the search query as well.

The tag is meant for issues related to adding new language codes, or changing/removing existing ones. Does that make sense?

Thanks for the explanation, makes sense!
In theory https://www.mediawiki.org/wiki/Phabricator/Project_management/Tracking_tasks explains the procedure to replace a Tracking-Neverending task.