I personally hate translation system in Invision Community.
We cannot add custom language strings.
We cannot filter language strings by application.
We cannot download translation for one application.
We cannot add update check url into our language packs.
We cannot translate language strings of plugins.
We see technical empty strings, you mentioned.
Users unable to see if 3rd-party language pack is out of date and new version is available.
No way to add copyright info, author website or even their name.
Hate it. Nothing changed since 4.0 Release Candidate.
This is a customisation for our own community and unfortunately not available in the downloads app.
I have raised an internal suggestion for this, because I think that it would make indeed sense to have such a feature in the core.