Tressau modified the rules for the Kaiserspiel (e.g. castling rule is different in the Archiv der Spiele description) and practically developed the rules for the Sultanspiel himself based on Peguilhen's initial - but never fully developed - idea. Later sources are ultimately based on Tressau, with errors. Thus it's Tressau's rules that should be taken as definitive, the illustrative games were played by Tressau himself and after his own rules, so there is hardly any chance for a misunderstanding.
There's a discussion of all that in my paper in press, I'll provide a link when it's published.
Tressau modified the rules for the Kaiserspiel (e.g. castling rule is different in the Archiv der Spiele description) and practically developed the rules for the Sultanspiel himself based on Peguilhen's initial - but never fully developed - idea. Later sources are ultimately based on Tressau, with errors. Thus it's Tressau's rules that should be taken as definitive, the illustrative games were played by Tressau himself and after his own rules, so there is hardly any chance for a misunderstanding. There's a discussion of all that in my paper in press, I'll provide a link when it's published.