First, I am a tool designer, tool maker and machinist. The form tools I know about are of two types. One type is held on a slide a forced against a rotating piece, as in a Davenport or Acme-Gridley bar machine. The other type turns in a spindle on a milling machine or a router to cut shapes. In all cases, however, the shape cut is the profile of the cutter. The only deviation I've seen is in the shape of parts cut with a screw machine form tool with too much rake because it was notched too far below center. All of these form cutters, including most ground forms, are round. You would model all of them as simple revolved protrusions. Where they may not cut well on the sides of the form, it is because of lack of back or side relief, thus rubbing instead of cutting.
Obviously, you can have a Pro/e part which doesn't agree with the shape of the cutter or the machined part. Still, you have to check and be sure which is right. And, even if the machined part is right and the Pro/e part is not
100% correct, there are just a couple instances where this makes any real difference. One is where you are designing the form tool and the other is where you are inspecting machined parts against the digital model through a laser inspection system.As to your idea of making a variable section sweep, the technique is not correct. The x-vector trajectory can't be at right angles to the main trajectory. If you are trying to rotate a section, you need a rotational blend. Or, as I said before, a simple revolved protrusion. Or if you are trying to make a feature which grows or changes for while it sweeps, then make a swept blend.
Everything I've said so far may not be to the point. Your description of what you want to do starts in the middle of the problem. More of the big picture, what you are working on, where in the process this problem arises might help encourage a response that's more to the point. In any case, the whole business is very difficult to visualize, which is precisely the point a 3-d visualizing system like Pro/e. If you could include a JPEG of an errant part or tool, it would be most helpful.