Now the glider has lost 30kt of airspeed, and needs to readjust by closing the airbrakes.
Airbrake controls the glide angle. Elevator controls speed. At least that's what I was taught.
You can try retracting the brake and stuffing the nose down but it will still take time and height to accelerate. While you trade height for speed you descend through even more wind shear. Might not be able to recover your speed fast enough. It's one reason why you carry extra speed on approach in windy weather.