Bleed port repair on Shimano road brake lever?
I would re-tighten the bleed port screw and watch for leaks. If you get no leakage and the screw does not loosen then you are fine.

A partially damaged thread should not be a problem as the bleed port screw does not have any load on it. (There should not even be any fluid pressure on it during braking as the reservoir is cut off from the line by the piston when the lever is pulled.)