The current version does not seem to have any way to define a global currency format, instead, we have to define it every time a piece of currency is outputted.
I believe it would make sense to define the locale once in the config file, then all other locale-related functions will automatically convert based on that defined locale.
I believe this should be put into consideration for future Yii releases. As I said before, if you are going to display the language in en_US, you will probably want the currency defined there as well.
Yes, CNumberFormatter may be tricky to extend - cause of private properties, though I needed not formatCurrency() updates.
I’m extending CNumberFormatter putting NumberFormatter class to components directory and having probably all the parent class code copied into a child. It’s kinda ugly solution, but I couldn’t find the better one for my needs yet.