Hello @Christian-0,
Thank you for reaching out to us. I am a bit confused by your question. A soft body simulation is characterized by the fact that it gives up the idea of a geometry transform with governs a geometry as usually applied in computer graphics. In the end this means that the transform of the object (BaseObject.GetMg) will not change but the points will and with it the bounding box of an object. Below you see a soft body cylinder falling. Its transform, the axis, never changes, but the bound box does. Animated are here the points, not the object, hence the term soft body.
In the API you can get the bounding box values with BaseObject.GetMp and BaseObject.GetRad. When you want a transform, a matrix for that, you would have to compute that yourself. The matrix manual dissects how to construct matrices.
Cheers,
Ferdinand