Purge already answered that board. He said, "This is correct. He's an "extremely hard" opponent that we placed in the impossible category for BQs to add a bit more variety. (Though eventually we'll be able to change what tokens opponents drop! And we'll remedy this then)"

He actually is only an extremely hard challenger. This is not a bug.

He'll be fixed once they can change what he drops. In order to keep him as a extremely hard right now (since that is what he is) he has to drop the same level token. I can ping here to see if there is an update but I am assuming they haven't been able to change it yet.

General Error is in the impossible queue for a bit of variety as there aren't many impossible challengers to choose from, and he is occasionally as difficult as some of the other impossible challengers. He's not getting removed.

He does have a low chance to drop an impossible token, though.

Please see above. Locking as this is again not a bug.