I have a theory......
This is from what I noticed, but I was not watching like I should all the time trying to stay steady, so if I'm wrong help me out.

Green only = cleared contact.
Green + solid amber = contact
Green + blinking amber = taking fuel
Red + solid amber = getting too close, fuel transfer stopped.
Blinking red = break away
All lights blinking, green, amber, red = I believe fuel transfer complete..... because I did not get a voice confirmation. Also can't remember how many pounds in the Hornet when tanks are full.
I do remember 6000 in the left and 6000 in the right when I broke away.