There's one thing about the Rhine Tribunal that should not come up as a surprise in a saga - unless characters are stranded there by a teleport gone wrong or such. You find it in GotF p.24:
... in any dispute that could otherwise be decided by certamen, a higher-ranked magus automatically has priority, as granted by the Rhine’s Peripheral Code. Thus, if a master and a journeyman quarrel over ownership of some vis in the woods, the master automatically has the right.
You should inform players up front of it and discuss it, as it puts political maneuvering in the Tribunal way above certamen: the one who has an Archmage on his side wins.
There's a summary of GotF on this forum, which was meant for Project Redcap.