I'm running the latest version of Aspose.Cells (7.6.0), and I've run into something very weird. The net2.0 version of the binaries works correctly when called through Interop, but the net3.5_ClientProfile one seems to be missing a number of interfaces. The use of generics in classes like RowCollection means that interfaces such as IList are no longer exposed through Interop.
I understand that this is a limitation of Interop, so I would recommend that you do NOT include an interop type library with those versions of Aspose.Cells.dll that don't work properly with it.
Regards,
Daniel