So we can’t import any spline objects form other software, that’s fine. But what we need is the ability to precisely set the spline control points up. There is no snapping for them, there is no numeric input, there is even no transform information available for the individual points (or at least I can find no information about it). All we can do with splines is just manually trying to make it right.
Splines are math, pure math, to draw them in the editor you simply have to work on the information I am writing about. Just make it accesible and usable as a control tool in the editors interface. Manually dragging the points around with no option to set them up precisely is not enough in some cases.