So we would need to create this language as I don’t think it exists currently. It looks like you’d need to add it to the list in application/models/Locale.php and also create a directory under locales for et_EE and copy a airtime.po and translate it. It’d be great to get this added as a pull request at github. We have done some work to make an easier way to translate things but nobody had enough time to fully implement it as of yet, so things are still needing to be done manually like this.
Let me know whether this is something that you can do on your own or if you need me to do some work setting up the pull request so that you can share your translated version.