Ok, here's how i do it in my Maplat framework: I added a plugin to TemplateToolkit. Every template wraps the (english) text that may need translating in a call. The TT plugin adds unknown texts to a "key" database, and for every "key" there may be translations in multiple languages. If the user selects a non-english language, the TT plugin retrieves this and returns it (else it just returns the english text).

For the translators, i just have two simple webmasks (create/delete languages and edit language translations). Oh, and there is a webmask to export/import translations so it's easy to get better/new translations from staging to production.