ORIGINAL: mesae
If kinetic energy is the energy of motion, it is therefore relative in exactly the same fashion as motion itself. Saying the glider has 200 knots groundspeed is equivalent to saying it has so much kinetic energy relative to the surface of the earth. Does the glider at 100 knots airspeed and zero knots groundspeed have zero kinetic engergy? Relative to the earth, yes (not counting it's vertical speed). Relative to the airmass, no.
OK, to keep things simple and consistent, stick to "relative to the earth" reference frame. I'm not sure you answered how the wind added all the extra kinetic energy?