My dealership overfilled my engine oil in my 2014 Forester in Jan 2019, by 2 litres. I complained of problems with the car chugging, sometimes severely, several times. I drove the car for 6-7 months like that, driving approximately 1,300 kms with the overfilled engine oil. The engine is a CVT. One time the car chugged consecutively, really, really hard, throwing me forward each time, almost stalling. I wonder if damage was caused at that time. There is approximately 33,500kms on the car right now. Problem has been corrected for about 2 months. Would any amount of damage be caused by this over filling?
Yes, overfilling can easily cause severe damage. Two liters of overfill is quite a bit.
The most concerning issue is if the oil is high enough so that the crankshaft hits the top of the oil and foams it up. Now you have an oil-air mixture that is being sorta pumped through your engine instead of the pure oil it's designed for. Severe damage to all bearings as well as the cylinder walls could easily have happened.
The only way to tell for sure is to disassemble the engine and check the bearings surfaces, cylinder walls, and piston rings.
There may or may not be other symptoms like low or fluctuating oil pressure, low or uneven compression, rattling or knocking noise from the engine.