Thanks for your inquiry.
BNO055 Pin 1 ID pad is an indicator to show where BNO055 pin-1 is located at the bottom side of BNO055 chip. It is helpful to place BNO055 on the PCB at the right orientation. BNO055 Pin 1 ID pad is not connected to anywhere inside BNO055 chip. So there is no problem if you ignore this pad when you design your PCB layout or this Pin 1 ID pad is shorted to other pins during soldering by accident.