I created a Localizable.strings file and the translation works fine. But there is a special case where in english there is one word for singular and plural, like \'series\'.
How I do it is do my localisation names as follows: series = "series" and "Serie" and series_pural = "series" and "Serien". Then the system just looks for a _plural afterwards and if it exists then it'll show it (if you tell it that its a plural word that u are localising). Another way would just you handle whether or not a word is a plural on a case by case basis.