Nine Collection extension messages are documented as "Unused at this time" in qqq. To see a list conveniently, do any of these things:

• Look at https://translatewiki.net/wiki/Special:Translate?filter=&action=page&language=qqq&group=ext-collection and search for "Unused" in the translation column.
• Look at https://gerrit.wikimedia.org/r/plugins/gitiles/mediawiki/extensions/Collection/+/refs/heads/master/i18n/qqq.json, and search for "Unused".

If they are indeed unused, they must be removed.

I didn't have time to verify each of them, but I did check coll-noscript_text and it was removed back in 2008.

To remove them:

• Verify that they are unused: check that the key is not used anywhere except the i18n/*.json files.
• Bonus (not necessary if you're certain that they are not used): Find when was the message removed, for example using git bisect.
• Remove them from i18n/en.json and i18n/qqq.json. (No need to remove from other json files. This will be done automatically.)

For (just a bit) more information about removing messages, see https://www.mediawiki.org/wiki/Localisation#Removing_existing_messages .