I tried it and this is the output:
outputs
tensor([-14.7144765854, -14.7144765854])
targets
tensor([-14.5868730545, -14.5640010834])
No diff in intercept_Cu
No diff in slope_Cu
Diff in linears.Cu.0.weight
No diff in linears.Cu.0.bias
Diff in linears.Cu.2.weight
No diff in linears.Cu.2.bias
Diff in linears.Cu.4.weight
No diff in linears.Cu.4.bias

Optimized parameters for Cu symbol
Index 0
Parameter containing:
tensor([[ 8.5844440460e+00,  5.7265067101e-01,  9.7642364502e+00,
         -6.3340994529e-05, -6.5706312656e-01, -1.0317638516e-01,
         -8.1990205217e-04,  3.8604885340e-02],
        [ 5.6350793839e+00, -2.3107304573e+00,  3.0389562016e-04,
          4.8599953651e+00,  6.9255195558e-03, -1.2411396503e+00,
         -1.9741505384e-01,  1.5696491755e-04],
        [-5.0464026572e-05, -3.3354687691e+00,  8.9420490265e+00,
          3.8780815601e+00,  2.3376888130e-03, -5.5896580219e-02,
          1.3885598630e-02, -1.0426228866e-02],
        [ 9.5443532337e-04,  6.6207236052e-01, -8.9323358536e+00,
          6.4504299164e+00, -5.6406411204e-06, -1.3022724390e+00,
         -6.7651176453e-01, -4.0060423315e-02],
        [-7.3771867752e+00, -2.8842912674e+01, -1.2261917114e+01,
          2.0418181084e-03, -3.8052463531e+00, -4.1274856776e-02,
          7.0336312056e-02,  7.7507920563e-02],
        [ 1.1060595512e-01, -3.2884517312e-01,  1.3592758179e+00,
         -3.1894344091e-01, -1.7296176404e-02, -6.2223523855e-02,
         -1.0991756916e+00, -1.0611775797e-03],
        [-1.0529378653e+00,  8.7992340326e-02, -3.9956837893e-02,
          5.1080572605e-01,  7.3425645828e+00, -1.4347046090e-05,
          4.9415111542e-02,  1.4767070770e+01],
        [-6.3522720337e-01, -3.3820127137e-03,  1.0707162857e+01,
          1.5198823530e-03, -5.2807319164e-01,  5.2644854784e-01,
         -1.2110622600e-02, -2.9190010391e-03],
        [ 3.0526014045e-02, -1.3536047190e-03, -3.8478989154e-04,
          2.9252339154e-03,  5.4483871460e+00,  7.9564154148e-03,
         -1.8055616617e+00, -6.4464583993e-03],
        [-4.6962329745e-01,  8.6185136752e-06,  2.4837136269e-02,
         -4.1209143092e-05,  4.2492513657e+00,  8.4312686920e+00,
          1.9236560433e-07,  3.2226529717e-01]], requires_grad=True)
Gradient tensor(-0.0052632340)

Index 1
Parameter containing:
tensor([ 0.3178096116,  0.0436611772, -0.2040621340, -0.0848887563,
         0.2899220884, -0.2525188029,  0.3507566750, -0.1945837736,
         0.1707542241, -0.0507352650], requires_grad=True)
No gradient?

Index 2
Parameter containing:
tensor([[ 9.4454865903e-03, -3.8685989380e-01,  2.8510479927e+00,
          1.6451107513e-05,  7.2450813605e-05, -2.4000716209e-01,
         -1.0067681968e-01, -6.8808451295e-02, -1.3941727579e-02,
         -1.1572503299e-01],
        [-4.0232582251e-05,  1.5237447619e-01, -8.4863287952e-08,
         -3.3062148094e-01,  3.1492298841e-01,  7.1657931805e-01,
          6.5576374531e-02,  5.8732334524e-02, -1.4156305790e-01,
         -1.1431868374e-01],
        [ 3.6709681153e-01, -5.6241098791e-03, -1.8890530029e-08,
          2.2205217101e-04, -3.8731803894e+00, -8.4317040443e-01,
         -3.5567022860e-03,  7.6645493507e-02, -1.7931096554e+00,
         -2.0117998123e+00],
        [-2.6692817919e-03,  2.3045387268e+00, -1.9369858503e-01,
          1.1653967202e-02, -1.5044789314e+00,  2.6386910677e-01,
         -1.8918566406e-02,  2.4579927325e-02, -8.7022192020e-05,
          1.4020656636e-07],
        [ 2.8100815415e-01, -1.4995394740e-03,  3.7862854004e+00,
          2.3118360519e+01, -1.2707098722e+00, -8.9394124225e-03,
         -7.3012824942e-06,  6.0733418650e-07, -6.8714976311e-02,
         -1.7940466932e-04],
        [-1.1861760616e+00, -1.7072351277e-01,  7.4709236622e-02,
         -1.6057054698e-01,  1.0028474033e-01,  4.4707970619e+00,
         -3.2747825980e-01,  1.8114055820e-06, -6.0276460648e-01,
         -2.9894538879e+01],
        [-2.0331549644e-01, -9.2998981476e-01, -2.3422073573e-03,
          6.5794992447e-01, -4.0772670507e-01, -1.7908929586e+00,
         -4.3703973293e-02, -2.3664340377e-02,  3.4835241735e-02,
          7.3881530762e-01],
        [ 5.4340696335e-01,  1.3241521083e-04, -3.2028186321e-01,
         -1.6411489248e-01, -8.0035102367e-01, -1.0085972399e-01,
         -2.3231016099e-01,  9.6048679352e+00, -1.3925330162e+01,
         -8.2148885727e-01],
        [-6.0046720505e-01,  1.0296676308e-02, -5.9643266723e-03,
         -2.2244569845e-04,  1.5874393284e-03,  9.7708535194e-01,
         -7.4371069670e-02,  8.7442662334e-05, -2.0362114906e-01,
          1.5027550697e+01],
        [ 1.2441553175e-02,  3.5354614258e+00, -4.9783945084e-01,
          1.0338279605e-01,  2.9940547943e+00, -1.0266765952e-01,
          1.2045311928e-01, -3.1238024235e+00,  3.3330893517e+00,
         -4.7617787123e-01]], requires_grad=True)
Gradient tensor(0.0078644780)

Index 3
Parameter containing:
tensor([-0.0413947999,  0.2711434066,  0.0748769045,  0.1031675935,
         0.0756872594,  0.3022760451,  0.2172745764, -0.2653046250,
         0.2037093341, -0.0445466638], requires_grad=True)
No gradient?

Index 4
Parameter containing:
tensor([[-4.1193764657e-02, -3.5373184830e-02,  1.8808110617e-03,
         -3.8154840004e-03, -2.7028546333e+00, -1.3087383270e+01,
         -3.1675234437e-02, -7.3683762550e-01, -4.4051003456e-01,
         -1.4208417851e-03]], requires_grad=True)
Gradient tensor(0.0099373152)

Index 5
Parameter containing:
tensor([-0.1635424048], requires_grad=True)
No gradient?

Now, by downloading the gist the changes can be made in L-342 1. Thank you very much for your help. I am embarrassed but honestly lost.