If it has a flared seat on the line I wouldn’t bother with a thread insert. However if it’s an o-ring seal as long as its straight and snuggled up it should still seal fine.
I agree with college man. I would bet camshaft endplay is not that far out if it is out of spec. You must test the sensor if you have issues with a new sensor. It is not that uncommon to get a bad new sensor out of the box.