I realize I misread the OP, and I think a few others here did as well.

If I now understand this, the OP already has a working 11sp rear shifter. It was the FRONT that was damaged, and it has already been replaced.

But with the front shifter he also got a 9sp rear shofter.

He seems to think that because he has this extra shifter, he needs to use it, even if it means spending a bunch of extra money to do so and even if that means a downgrade. Everything he is talking about doing is more expensive (in both the short term and long term), and results in a downgrade. Whether he is willing to hear this is another matter.

Nothing currently needs to be done to the bikes drivetrain, It works fine. The best thing for the OP to do is throw the 9sp shifter into a parts bin or sell it.