Recently I had to deal with a Rails project started by 4 months.
The project was developed in a rush, so nobody took care about internationalization. Finally we had 100+ untranslated html partial, and nobody would try to translate them manually.
So I created a gem that extracts hardcoded strings from partials to locale files.
It's not perfect, but it did the trick.
You can find the gem here
And this is an article I wrote about it