Regarding my first statement, I was confused by the fact the LIN component has no interpolation option (black label on the bottom) until it gets fed with inputs.
But indeed, as soon as it is, it defaults to C_DIS.
You are right regarding the tool offset : I see how taking out the interpolation just before the offset might create a tool mark.
Maybe you could propose a new tool offset type that would "overshoot" tangentialy the last frame along the trajectory and THEN offset in the tool axis.
The input would be the "overshoot" distance + the "Offset" distance and it would add a little CIRC movement to blend the trajectory and the offset...