It will never be perfect, in my opinion not even with Alias, also I have seen them that many go crazy to get surface tangent to an other and sometimes for a simple bevel they take half an hour or more, and they are professionals users, however I found a way to do it with FreeCAD and uses only one nurbs patch, a totally different method from Moi3D but I am already satisfied because I managed to do it with a decent transition now, with the NSIDE command, before it could not execute the command without surfaces.
Below the try with FreeCAD and the control point in Moi3D it's a bit messy