Hi friend, the regular Extrude Tapered option only works on planar objects. To speed up your case there though you could use the Construct > Offset > Shell command.

To use that you can skip creating the second surface and the lofting, instead start with just one trimmed surface:



Then run Construct > Offset > Shell and give it a thickness. That will generate an offset surface which for a sphere will be a scaled sphere, and it will do a loft between the edges of the offset and the original for you, giving this result:



- Michael