For using 'Special:AggregateGroups' in the big multilingual sites with many numbers of translatable pages (see as example meta:Special:AggregateGroups) may be useful addition next option:

• list of pages that are in translation, but not part of any group (as automated section)

In other words, as a result of this option, this special page will always display all translatable pages - either as part of aggregated groups, or in this new section.

See also T179512 with list of wishes for Special:AggregateGroups