Not sure that I completely understand your query. But probably you are looking for something like this:
1) Get the faces of fillet feature: Feature::GetFaces.
2) Get edges of these faces: Face2::GetEdges.
3) Get end points: Edge::GetEndVertex/Edge::GetStartVertex.
if you clarify your requirements I think we will be able to provide more help.
Application Engineer at Intercad
Tel: +61 2 9454 4444
I got it!
I was asking the wrong question that's why you didn't understand my requirement
I should have asked how to get the StartPoint/EndPoint of an Arch since the created fillet in sketch will be converted to Arch.
And I already know how to get what I want. Sorry for my misleading question.