What happens if you overfill
While chocolate milk is tasty and good to drink, fluid that looks like chocolate milk is not good. [ to drink or for your trans ].
First, how much over full is it [ do you not have a dipstick? ]
Second, what type of trans is it, some transmissions are very sensitive to too much fluid. Such as the thm400.
A little over may not be a problem, but too much will cause all sorts of problems, on some units.
Have you pulled your vacuum line off, at the trans, to see if fluid would run out [ it should not ]