The orange edges in KISSlicer as just notifications that there *may* be problems with that edge.
KISSlicer will flag actual bad edges (for example an edge that only has one triangle attached to it, or an edge where the neighboring triangles are 'wound' differently (essentially one pointing in, one pointing out)). But KISSlicer will also flag edges that are technically legal, but may give numerically unstable results, such as high-aspect ratio triangles, or 0-area triangles (commonly used to "fix" T-junctions).
I just load the mesh and slice. Then I scan through the paths looking for anything weird, and if it happens next to an orange edge, I know I need to fix something in the source mesh. If nothing weird shows up, ignore the orange edges. [8^)
Jonathan