There's this patch: https://gerrit.wikimedia.org/r/c/mediawiki/extensions/Translate/+/902018/2/src/PageTranslation/TranslatablePageInsertablesSuggester.php
It did what's needed and fixed the bug in question, but I was wondering: Do we usually need the /u flag in regular expressions? If we do, then should it be documented on this page?
And can the automatic tests identify when it's not used?