Data WP MU 3.9.2 Recently I discovered that…

Data: WP MU, 3.9.2

Recently I discovered that my custom Akismet’s localisationLocalization Localization (sometimes shortened to "l10n") is the process of adapting a product or service to a particular language, culture, and desired local "look-and-feel." was replaced by default one – 2 questions about auto updates and languages:

1) Does WP updates smth in wp-content/languages folder when auto updates?
I would like to keep all my custom localizstions (of all the themes and plugins I use) in this folder but now I am afraid that after WP auto update every custom localisation just disappear or will be replaced by default. Should I be worried about this or WP does not effect these?

2) What can I do to keep Akismet’s custom localisation in safe from the pluginPlugin A plugin is a piece of software containing a group of functions that can be added to a WordPress website. They can extend functionality or add new features to your WordPress websites. WordPress plugins are written in the PHP programming language and integrate seamlessly with WordPress. These can be free in the Plugin Directory or can be cost-based plugin from a third-party or WP auto update? OR: How do Akismet update it’s default localisation and where Akismet stores it?