Okay this is a more complex form a chess than standard, but they are able to complete a match in 27 minutes? Even fast chess games are timed at around 15 minutes for each player. 27 minute game of a more complex version of chess is unlikely. Even if Desir makes his moves instantly because he knows what plays Joan is making from experience, I would imagine that Joan would think out his moves properly each turn.
Also double move for being in a pawn lane seems pretty overpowered. It's pretty easy on a larger chess board to keep a pawn stationary after you set them up on a diagonal, but I guess there's something else to it besides "didn't move the pawn last turn". A double move for a king piece is extremely useful and since they don't specify that the lane has to be in front of the pawn, then that could lead to some back row shenanigans. Rooks in particular would have an easy time picking off any unguarded piece making the game even slower since you have to pay attention to the rooks position and your protection before making any moves.