Sometimes Filter parameter would perform strange upon Smart Corners, for example, Offset Curve would make the starting and ending nodes of a corner segment away from the Origin:
Say, I have a glyph like A, with the Smart Corner B, and the final shape is C.
I added an instance with the filter parameter Offset Curve. Both the base shape (D) and the corner component (E) has been offset. The instance now looks like F.
I suppose I can add a custom parameter Decompose Corner, similar to Decompose Components, so that the offset filter could work on C as a whole, creating the final result like G.