Yes, that one is quite hard to get right for normal chess engines too, and it usually isn't done. E.g. if both sides have only a bishop left, then if the two b

Yes, that one is quite hard to get right for normal chess engines too, and it usually isn't done. E.g. if both sides have only a bishop left, then if the two bishops are on squares of the same color checkmate isn't possible, but if they are on different colors then checkmate is possible in a corner. Or pawn formations in the middle of the board that prevent breakthroughs. Most online chess sites only consider the obvious case of king + bishop or knight vs king to be a draw under that rule (and king v king, obviously).