Engine could be toast. I suggest having the engine diagnosed at another shop to determine next steps. I have seen this happen twice before where the shop doesn’t drain the oil reservoir overfilling by 6-7 quarts.

You could had dodged a bullet but...

The concern is the over filling reduces the amount of space there is for the oil vapor to be removed from the crankcase fumes and the efficiency of removing the oil from the vapor is reduced.

The result is more oil -- in the form of vapor -- gets routed to the engine where is it burned.

Oil in the combustion chamber negatively affects the ability of the gasoline to resist detonation thus under hard acceleration this could be more likely to occur. Sure the DME will detect this via the knock sensors before it becomes a real threat to the engine and back off timing and maybe reduce boost (or the timing being backed off has this side effect) but the bottom line is the engine makes less power due to the oil vapor in the intake charge.

There is the concern about engine deposit build up, too.

Might add in severe cases of overfilling there is the risk of oil from the vapor wetting the intake walls then upon engine shut off this oil draining down into the engine, into a combustion chamber if the intake valves are open, or collecting on top of the intake valves if they are closed.

(This happens as we sometimes see the cold engine making some smoke upon startup. This comes from oil that has collected on top of the intake valves or has managed to get into the cylinder via open intake valves.)

Upon engine start this oil could be enough to result in a hydraulic lock up of the engine.

I would flatbed your car to another shop for further diagnosis. Have the oil tested for metal because of potential damage to the rod bearing in case of a hydraulic lock of the engine.

Good luck!