Well too late I guess...
I put 5 liters in & drove about 18km & the transmission shift so nice & smooth it's almost like having a brand new one , it doesn't slip anymore but it didn't get all the "power" torque back
Could having too much oil (1-2l) makes the transmission working worst? (I think not but not 100% sure?)
As far as I know having too much oil/fluid is only bad to blow gasket or seals
Or maybe all it needs is another liter of transmission fluid?
As far as the check plug it's not easy to reach if you don't jack the car up (unless your thin) or have long arms , really stupid idea from GM to not have an transmission dip stick...
