If I understood well, all skins are only written in the particular languages the programmer added. So names of months, weeks and the boxes "To do" and "Agenda" can't be changed. An exception is shadows4, where you can change a lot. Or am I wrong and those features actually are open for language change?
As I noticed, there aren't many skins in Dutch language . As I like to be addressed in my own language, it would be nice if all skins would be programmed in a way that the skin features can be randomly changed by the user to his own language.
As a matter of fact, I like standard skin shadow a lot except for the ugly red Today circle marking, which almost hides the day number, could it be changed to users preferences?

If the skin uses normal text to draw the headers and the day names they are automatically translated to the chosen language. If the skin uses bitmaps they naturally cannot be translated unless the skin author provides different versions of the images with the skin.