The scripts are relatively simple, they use FEMAP's face picking function to pick the face of an element. Within this command, the user is prompted for a single face, and an angle, FEMAP then walks the connected free faces of either a shell mesh or solid mesh, stopping when the face to face angle exceeds the input value. It first script then lists these faces, together with their areas, and then a final total area.
The second script expands on this and lists the nodes of each individual face.
I am not familiar with NX Open code, I would advise posting on the Simcenter 3D Forum and see if someone there can provide advice on creating an NX Open equivalent.
If your meshes are in Simcenter 3D/NX CAE, you can export the model as a NASTRAN file, and then use FEMAP and your scripts to extract the same information.