But there’s no denying that FreeCAD is still a bit of a lifestyle choice :-) I love it, but I don’t try to sell everyone on it yet.
It might be possible to predict which edges would have problems, but I think that would involve repeating geometry calculations outside the geometry kernel?
Specifically the main problem with fillets/chamfers in OCC is that the new face cannot completely consume/replace an existing edge.
That is to say -- I think!? -- that one of the edges of the new fillet/chamfer is always an existing edge just displaced, and no edges are destroyed. If an edge would be destroyed, then it fails?
But this is just my colloquial/folklore understanding.
There have been newer versions of OCC that FreeCAD has not yet switched to, I think. (And there is a new (Chinese) fork, called OpenGeometry.)
So maybe there are some fixes already in the pipeline or in the future. But they are somewhat out of the FreeCAD project's control, is my understanding.