There are various major artefacts when using anything more complex than basic primitives however.
Distance map is known to produce artifacts in some cases. If your cutter has sharp angles, you can try to add tiny amount of chamfer and see if that helps. Also try to subdivide intersecting objects - that might help also.
Ive noticed you get a really thin slice of the base object material before it changes to the inside edges. Is there a way to control the thickness of that edge?
Are you using round corners on that material? Try to remove it and see if thin line disappears.