Yeah, it's a very complex problem.

Those "Big CAD" programs (ones based on the ACIS or Parasolid geometry kernels) are better at doing it, they've got quite a lot of people working on it and have invested a lot of effort handling a large number of special cases. But there can still be fillet problems even in there too.

I do expect that the filleting in MoI will improve over time, but it will take a while. But I think that this particular problem here probably won't be too bad to get fixed.

- Michael