I've been moving some hardcoded string over to the language files. The changes are only in
english.php. In order to avoid partially updated language files, I don't think it's wise to start updating other language files right away. New constants might still be added.
Some weeks before the final release of the next version, we'll mark the language file version as final and let the translators do their magic. Ideally, updated versions for all language files would then be able at the time of release.
If you come across hardcoded text, feel free to let one of the developers know. I know some pages like the bookmarklet page are entirely hardcoded in english. Didn't quite know what to do with that...