Well done, good historical legwork.
Boettner has Joan of Arc condemned to the stake by the Pope....wasn’t it a Burgundian bishop who presided over her trial?
A Burgundian bishop who was in the pay of the English, who wanted Joan, their mortal enemy, dead.
Her trial was also very irregular according to canon law. I believe the law required three clerics to sign off on her condemnation; they had one.
Pierre Cauchon claimed jurisdiction over Joan of Arc because his English allies captured her in Compiegne in his diocese.
However, as a Catholic from Domremy, she was entitled to demand that she be tried in her own local ordinary's court - which would have resulted most likely in a controversy over canonical jurisdiction which would have to be resolved by a higher authority, likely Rome.
Cauchon ignored canon law and proceeded to preside over a trial for which he had no legally established jurisdiction.
The Pope had no role in her conviction or execution - when he learned of what happened he overturned the verdict and leveled canonical charges against Cauchon, who refused to answer them and fled his diocese to take refuge in English-controlled territory.
The entire trial of Joan of Arc was conducted against canon law and without the Pope's permission.