Hello!
I have the same problem with Localization, it doesn't work any more.
The first time I try to use it with the example scene, it works perfectly, so I've replaced the Localization.txt file by a custom Localization.csv file to try the csv, and it also works. Great!
But after moving the csv file in my Assets/Resources folder (and deleting the old one in NGUI examples folder), Localization was broken. It looks like it only reads the first line (KEY,English,Français, etc...), all the other keys are not found (in inspector preview and at runtime).
No idea of what happens, I was a bit lost, so I decided to delete NGUI plugin and reimport the same version of NGUI. But it did'nt solve the problem, the Localization doesn't work even in the example scene.
I'm using NGUI 3.5.9 & Unity 4.3.2
Any ideas of what is the problem ?