Those properties are mostly part of some object that, in turn, is a property. For example, CornerRadius is a property of the Drawable.
However, some properties available in the designer scripts are not available elsewhere (Right, Bottom, HorizontalCenter(?), VerticalCenter(?) and so on). That's a Little sad, as they are quite useful. Sure, they are easy to produce from Left and Width et cetera, but for pure code readaility, I would very much prefer if they were available in code as well. Once you start moving things around in code, you tend to get long lines, which would be much neater if those properties existed.