1) Gap:
I do agree it would be good to promote these backlogs, as two of the easiest ones for newcomers to work on. (Although there are guidelines and best-practices, and any backlog promotion should clearly point to those documentation pages, so that newcomers can have a ready-reference).
2) Translation
I
also agree that a machine-translation /suggestion/ or /hint/ would be a
nice option. The main concern is users who don't understand
the limitations of machine-translation and whom must resist the urge to just
copy&paste. (This goes for both language-fluency, but also for technical-vocabulary fluency, e.g. I could not give a confident description of most chemistry or physics articles, even with numerous machine-translation-based suggestions or the article itself!)
I can't see anything specifically about this in Phabricator, so it's probably worth filing a feature request, unless someone else points out a task I missed, or raises an overwhelming concern. [Note: a semi-related task to link in the SeeAlso of the new one: T71345]
3) Tools:
Is it currently possible to get a list of items without a label/description in language X?
I tried a few weeks ago, and the onwiki Special pages were broken. I filed
https://phabricator.wikimedia.org/T157884 " to cover this problem.
Are there any other tools which help with listing or processing these particular backlogs?
Quiddity
(Volunteer hat. This is just the address I use to subscribe to this list)