I've thought that the key theme in both "Anathea" and "Seven Curses" was that of supernatural vengeance. The gallows groaning or the ground beneath the gallows groaning is the natural order asserting itself when human justice fails.

The payment to the judge is not a bribe, but a payment of what Germanic tribes called "weregild" - practice common to many tribal societies - that could be demanded by the relatives of a murdered man in lieu of the death penalty for the murder. This restores the social order by paying to the relatives an amount equal to what the dead man would have contributed to their clan. In both cases, the judge accepted the payment, but killed the thief anyway. This was the unavenged injustice. The judge is also cursed with a disease that cannot be cured by natural means. Thus, justice is meted out by supernatural means.

We have something similar in the "Bonnie Swans" or the "Twa Sisters", where a harp made of a murdered girl's breastbone and hair sings out the name of the murderer. In this case, we can only assume that justice will be brought about by the girl's relatives having the murderer arrested; but, it is initiated by supernatural means.