In the big multilingual sites with many numbers of translatable pages, using 'Special:AggregateGroups' may be caused some problems. See as example [[ https://meta.wikimedia.org/wiki/Special:AggregateGroups | meta:Special:AggregateGroups]]
Main problems/wishes
1. Strongly needs automatic table of content (list of aggregate groups) / or collapsible mode - T179798
2. Needs a list of pages that are in translation, but not part of any group - T179799
3. Needs support for the hierarchical nesting of aggregated groups (if this is not supported for translatable pages; if supported - how to realize this?); or another way for organize these groups - T179800
Backstage issues:
4. There is no annotation (a brief description of the purpose of the page - as in another special pages, through "`$specialPageName-summary`" message),
5. There is no link to the help (as in another special pages); //currently no appropriate help page, but (ideally) should be separate help page for each special page in use;//
Related issues:
6. from side of each translatable page, would like to understand which aggregated groups it belongs to.
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//PS: See also [[ https://meta.wikimedia.org/wiki/User:Kaganer/Translator%27s_feedback | full wishlist from me ]] (mainly in Russian); this list will be transferred into Phabricator gradually.
//