Although , the temperature is the same as the front side temp, but the oppenheim element correspondence is distinct for both front and reverse side. We have two different oppenheim element elements (front and reverse), for each element in NX
Solution
For the reverse side coupling it is the top and bottom coupling in the mesh collector for 2D thin shell meshes. Use the Create Top and Bottom as Two-Layer Shells option in the Top to Bottom Couplings group.
Regarding the report of reverse side temperatures, you can do this by doing a temperature report and selecting the bottom side in the layer selection box at the bottom of the dialogue. It won't show up in the TEMPF however, unless you know the elements IDs.
Notes