You are certainly welcome to make any suggestions you wish, but as one who has spent a lot of time working with localization projects, I would actually strongly recommend against using empty strings. Using some default filler like [TRANSLATION PENDING] or some such will make it much less likely that you overlook it before shipping. Personally I like to use the localization tag itself (such as [MENU_OK]), so that I have an easy reference to what should be there. It's the same idea behind having magenta as a default texture: makes it nearly impossible to miss when running the game, making it much harder for it to slip between the cracks.
Just my two cents, your project can be done your way of course.
-Memige