We have this:
We'll probably be writing terms to wb_terms (see parent task T223792), but older entities will not have entries in that index until they are modified.
We want this:
We need to backfill wb_terms for older entries, from before we start(ed) storing terms there as soon as they change.
It looks like Wikibase/repo already has a maintenance script that does this (or at least something similar enough): maintenance/RebuildTermSqlIndex.php
- wb_terms has entries for all older entities