HI,
The PyMVA in ROOT 6.22.8 should support both Keras 2.3 and Tensorflow.Keras (tensorflow version > 2.0)
I think you should recommend people using tensorflow.keras for 6.22 and use add the option when booking the method, tf.keras=True. For example:
factory.BookMethod(dataloader, TMVA.Types.kPyKeras, 'PyKeras',
'H:!V:VarTransform=D,G:FilenameModel=model.h5:NumEpochs=20:BatchSize=32:tf.keras=True')
Note that the tutorials in tutorials/tmva/keras have been updated only for ROOT 6.24 to work with tensorflow keras.
If you are getting an error, please share your code and let me know the version you are using ?
Best regards
Lorenzo