The connector does have o-rings for the purpose of holding back the fluid. The pins on the plug run into the "conductor plate", which holds the solenoids and sensors that control the transmission. The plate is in the "wet" area inside so there is ATF behind the plug.

The reason I suggested dropping the pan was to inspect the condition of the conductor plate since it seems to me that something may be damaged in there causing a poor seal.

__________________
The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech