I just got the same thing on my Nexus7 (2013). I went ahead and installed it anyway with no issues. Only the initial message (and the comfirmation dialog to restart & install) were in Spanish. After the reboot, the update proceeded as normal (so far as I could see). I asume it was only the notification that got botched.
I understand being very hesitant though. I just happen to be one of those people who doesn't mind wiping everything out and starting over fresh every now and again.
