Some explanation on Offset Path and Contour:
In VectorStyler, the Offset Path is a shape effect, an adjustment of the shape of the object (like the other shape effects). It cannot change the style of the object (stroke color or width).
There can be improvements here in the new builds, but these will be limited strictly to the shape.
The Contour effect is an object effect, meaning that it blends fills and outlines between selected styles.
This can be improved in the future as suggested in the original post.