Hi!
1. presuming you dl the translation file (po & mo) ?
2. what have you renamed ? Normally there is nothing to rename for po/mo file names.
3. which code did you added to functions.php? Usually there is nothing to add there for translation.
See here for details: https://codex.buddypress.org/translations/
Note: Hebrew language file (buddypress_he_IL.mo) is uncomplete (72%), that’s probably why your register page is still in english.
There is also no PTE for hebrew which makes difficult for users to get the awaiting for validation strings.
The only solution for you is to download what is currently available in hebrew and to complete this translation yourself or to get in touch with this guy.
Perhaps you want to contribute to translation in your language? Read here if interested.
