@Kiki25, when you say "We let them know that the platform had mistakenly opened up the dates and they asked us to cancel the booking" who is the "them" and "they"? The guest or Airbnb?
In circumstances like this, where there is a system glitch, you should always contact Airbnb to have Airbnb customer support handle the cancellation. The customer support people can cancel a reservation without causing any penalty to you (so you can keep your SuperHost status).
Please contact Airbnb support right away and tell them that the reservation happened due to an Airbnb calendar glitch, and that you need the cancellation to be penalty-free.