From:  tyglik
stronger fillets operations : for example a fillet with a too high value should produce automatically
the biggest fillet possible, it should not fail.

I agree, it shouldn't fail, but... What is the "biggest fillet possible"? I am posting a 3dm file example with an object on which MoI didn't manage to create a fillet properly. However, I was able to manually trim and edit those surfaces to get a nice result. So from my point of view, fillet should lead to usable result at least...