[xmjvpkyq] asymmetric initial chess positions

Shredder-FEN seems to allow specifying Chess960 positions in which the locations of the rooks with which to castle differ between colors.  this allows scrambling the sides independently: 960^2 = 921600 initial positions.  many might be unfair, best analyzed by engine.  how unfair can an asymmetric initial position be?  are there forced mates?

do chess engines break or function poorly if you do this?  typical evaluation functions might penalize the loss of castling privilege equally for both colors.  this assumption might no longer be valid, though loss of castling always depends on how a game has progressed.

previously: there are even more possibilities if castling is forbidden or decreased, obviating the need for king between rooks.