Message echo-pref-beta-feature-cross-wiki-message still exists in en-gb (but not in en), but seemingly nowhere else, other than a mention in qqq
"echo-pref-beta-feature-cross-wiki-message": "Enhanced notifications"
"echo-pref-cross-wiki-notifications": "Label for a preference which enables notifications from other wikis. Only used if {{msg-mw|echo-pref-beta-feature-cross-wiki-message}} is not used.",
Should be cleaned up; probably neds the en-gb message deleting from translatewiki.net