All i18n (internationalization) file (*.po) master copies are stored as sub-pages of this page. See MoinDev/Translation for details.
If you get a status saying that there are a few untranslated messages, just search for !!!!, remember the english text from the msgid above it, click on edit, search for that english text (use your web browser's in-page search function), fix it and save it again. Repeat until all is translated.
The translations marked with -FIXME are orphaned and didn't get updated recently. If they go below some ratio of translated/total strings, they get removed due to quality considerations. You can help reviving them by fixing what's wrong and translating what's missing, so they can get included again.
he (hebrew) - send comments and patches to NirSoffer