I never worked with Joomfish, so I can't say, how this was working on the Joomla! 1.5 / Biblestudy 6.2. I guess, Joomfish builds up internal lists to translate the phrases of a page.
With Joomla! 1.7 Joomfish is not available. But both (and future) versions of Joomla uses language files to translate the phrases. Even more, Joomla! 1.7 forces the component developer to write translatable code with phrases that needs to be present in the language files. Example the phrase 'Please select a book' is no more valid, it need to be a key without white spaces (and other rules). So there need to be a language file with a row
JBS_SELECT_BOOK="Please select a book". Different files are needed for different languages.
I see an advantage of this system: Somebody who translates a component to another language will not build a private / internal set of phrases, but an official language file. This language file is easy to share among other users. This will enhance the usability especially on such big components like Biblestudy.
To translate Biblestudy (and other components) to other languages, the help of translation managers like
missing-T is useful. With this you see the missing phrases and get a fast first idea by integrated Google translation.
Every new language file is wellcome to be integrated and shared with the component. Please send it to us, if you have one!