No that is beyond my spatial knowledge at this point (minor pun) but if I have time I will look into it. So is the circle / radius search within the larger polygon the important aspect of what you are trying to accomplish. often I see circle / radius searches that are larger than smaller polygons like property outlines looking for intersection , seems like you are trying to do a small circle/ radius within the larger polygons is that correct? I think I'm lacking insight on what that accomplishes for your use case. What is your expectation when the circle intersects more than 1 polygon.
Note: it does look like we are in the middle of a major re-engineering of the spatial engine that is kind of indicated in the docs, some features are still there and marked deprecated as the new engine is moving towards more full features / feature parity with improved performance and accuracy.