It’s not poor pressure. It’s the wrong pressure that causes issues. The large spring cover is rotated to tension the spring so at the correct pressure the fuel is delivered (at the correct time) at the correct volume and in a good spray pattern...
The copper washers control how much the steel ones get crushed. They need both and they need to be new. 👍
It won’t cause damage. The hot spots are half an inch or so away from the end of the injectors.
Just clean up the washer seats in the head...