The speed of a windmill is often specified as tip speed ratio, the speed of the blade tip vs wind speed. For an aircraft, the similar number would be the glide number G_e. For a kite represented as a point looping downwind, zero gravity, the kite would travel at speed w G_e if w is the wind speed.

(please correct me if Im wrong here)

The TSR only applies to the wing tip. I am wondering what is the average «glide number», or mostly equivalent of a windmill. I guess the closest is to take the glide ratio at every point of the swept area, something like this:

\tilde G_e = \frac{1}{\pi r^2} \int_0^r{\mathrm{TSR} \frac{x}{r} (2 \pi) dx} = \mathrm{TSR} \frac{2}{3}

So my conclusion is that when comparing TSR to glide ratio (HAWT vs AWE), a smaller glide ratio would compare to a larger TSR. Eg: a TSR of 9.0 would perform similar to a glide number 6.0 AWE rig. The glide number would include an approximate kite+tether drag of course.

*Edit: as TSR is for a loaded windmill and glide number is for unloaded AWE, the comparison is not really useful. In practice, as flying speed is reduced by \frac{2}{3} when loading an AWE rig, the comparison of glide ratio and TSR is probably closer to 1:1*