Where are the OS X Language Files for Times and Dates?
It depends on where your looking and the relative application your using. 

If your talking about the ones in an application, they are bundled in the application themselves. In the example here for Skype, the .lproj is bundled in the Resources directory

 /Applications/Skype.app/Contents/Resources




The OS also stores the .lproj files in their respective bundles. By running this command in the terminal you can see where they all are, although you may need to filter a little bit more.

 find .  -name "*.lproj" 


The command will render something like this:



The same can be done for .strings,  although you may have some difficulty searching through them all.

find .  -name "*.strings"