Well, I hacked together AdafactorSchedule since Adafactor uses an internal scheduler and provides no access to it. We needed the workaround to prevent HF Trainer from failing when it calls get_last_lr.
Later someone pointed out that my hack was incomplete since it only reported the schedule for a single param group if I remember correctly.
As @sgugger mentioned it’s best for you too seek out an external-to-transformers solution, since Adafactor is scheduled to be removed in transformers-v5. I think our original copy came from fairseq.