As I understand the comments, the "square" chute would allow the "pilot" to
fly the canopy. They can be directed and with the ability to flare at the
end of the flight, just like with any other aircraft, they would therefore
have the ability to cushion the landing.

So, anyone trained would prefer a "square" chute.

So, accepting this as true, there is still one concern that needs to be
addressed. In a 2 place sailplane, the passenger gets a parachute. Even
though the pilot may have the training, the chances are very high that not
all of the passengers will have the required training, and may not
understand about flaring. Would that mean that the passenger should have a
round chute and just accept their lumps, so to speak?

Colin N12HS