This isn't a bug per say. It's a request for you to update the language files on Minecraft.

I've been putting quite a bit of time and effort into polishing off Spanish-Mexico. There's many errors still, and there's little to no activity on that language. So I'll take me a while to get through them all alone.

For example, when the Pretty Scary Update was released. There wasn't even a translation for Witch or Bat in Spanish. There wasn't even a translation for all the new items or blocks, and even from previous versions of Minecraft. There was also plenty of inconsistencies with grammar. Such as "Open to LAN" would be "Opening to laN" or "Open with lan". Also with people voting on misspelled words, for example. "died by magic" would be "died by magi". "died by magi" would be voted +3 by users. I still have little control on fixing that, and it would of remained the same today if I hadn't fixed majority of it with an alt account (betlhan is the alt account).

This lead me to volunteer my time for the Spanish speakers worldwide. Also for my younger siblings who couldn't even understand what words in English meant and had problems understanding due to the grammar. I'm sorry, I'm known to yack quite a bit, but I can't stress it enough, please Update the language files for Español-Mexico/Spanish-Mexico. They're not complete yet in terms of errors, but it's a much smoother ride for Spanish Speakers and at least we'll be able to understand it now to an extent. Thank you.

http://crowdin.net/project/minecraft/es-MX