Ok I made a mistake, didn’t realize that nonupdated weights are actually weights related to relationship_nodes from line 201 and are from the last update iteration (2nd) in the loop of model Scene_GCNN, so since they are not used as the output in line 209, they won’t be updated as they are not even needed. Thank you Stefano for trying to help me, at least I realized that I made a different kind of mistake.
I would close this question.