Yes, correct.
I don’t think it is MilkShape, it’s the Sur collision calculation algorithm - it does not know about concave shapes or shapes with holes because it uses extremities of the outer vertices surrounding the shape it is checking for collisions - these are being called “Bounding Boxes”. And it makes sense that the calculation is looking for penetration within the bounding box vertices.
But no tool will be able to split for example a sphere with a docking bay or hangar in it into 4 or more parts automatically.
We can do that, but then we also need to have cmp groups with the same name, so we may as well make the sphere in 4 pieces and give each one a name, and then sur exporter can easily make the convex sur parts for each piece.
As we all know, the limit of 18 parts is a problem for the tools we have, but this next sur tool will overcome that problem.