Hi, this may be a bit naive, but do you then pass on the parameters to BartTrainers as you would to Trainer, as such;
trainer = BartTrainer(
    model=model,                         # the instantiated Transformers model to be trained
    args=training_args,                  # training arguments, defined above
    train_dataset=train_dataset,         # training dataset
    eval_dataset=val_dataset,             # evaluation dataset
   compute_metrics=compute_metrics,
)