I tried the Ext.LocaleManager, but it doesn't fit my environment. I'm using my own one now, and it really works for me, and I'd love to have a few feedbacks. You can find it on GitHub:
I'm improving it now to support dynamic translation on the server side, a requirement which I have here in my company. People develop new views everyday, they upload them in production, but we don't always have translations for them, so basically we need the server to be able to know "what" translations need to be done. Meanwhile, the non-translated views (or resources) will be shown in English, the default language.