so ive got a transmissio cooler install a couple days ago, anyway
yesterday after driving the car home from work i was pushing the car
pretty hard, when i got home went inside for about 30 minutes came back
out and saw alot of coolant underneath the car. thought it was the water pump but it wanst, it was coming from the transmission side of the car.
the whole left side of the transmission was soak of coolant and atf oil so
i tried to find where it was coming from but couldnt find any trace of the leak
so i top off the atf and the cooland and wipe everything dried on the tranny
the next day i saw the tranny was wet again but this time is atf i still cant find were is leaking from.

 

Check on the top of the trans and towards the driver's side. There is a breather on top that runs off to the side, my friend's trans was belching it from there when it went poof.

 

Also, look for any hoses with pin-hole leaks spraying a skinny, high pressure stream. After getting home and turning off the engine, feel around that area by waving your hand in the surrounding area to see if a small high pressure stream hits your hand.

 

And you said a cooler was installed.. I would make sure both inlet and outlet hoses/pipes are heating up. You might have a blockage in it or something causing a pressure spike someplace forcing a leak. I would assume drivability problems would arise before a leak, but who knows.