As you can see the trim does not work. three lofts all joint into a solid and cut with a solid / curve just hides actually the shell top and bottom surface only the sides remain, or are hidden if I trim both sides as well.
Flatten the input going into the Brep Join component as at present it outputting the 6 input surfaces again and not a closed Brep.
You will also want to increase the vector lenght in the extrude component as at present it is to short to boolean all of the edges of so you solid difference output is giving you 3 surfaces and not just the middle 1. Best way to do this is just click on D of the extrude then manage vector lenght and increase the number to 4 say (thats what i did)