Fred,
You asked about if there was anyway to know if the transmission has been damaged from the coolant leak. If you pull the transmission dipstick out and get as much fluid as you can on your fingers. Look at the fluid very carefully to check the color. If it is a dark pink to light red, that is good. If the color is very light pink or clear, that could be bad. Also, rub your fingers together and notice how the fluid feels. If it is gritty (like hand cleaner) or if you see fine particles, you may have a serious problem.
BTW, this device is a heat transfer unit. It is using warm engine coolant to heat the transmission fluid that may not be able to warm up on its own. The fluid analysis with show if there is a problem or not.
Good luck,