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.)

I had exactly the same problem in Shimano 105 road shifter. I solve it by wrapping bleed screw with PTFE pipe tape and it did tightened to damaged threads in bleeding port.

I have the same problem with Shimano GRX leaver - just found that mineral oil leaked (a spot of leaking oil is visible). bleed screw can not be screwed in (it simply scrolls in the thread). The thread exists in the port by the way.

Thinking now how to fix such problem. For now I have next solutions on my mind:

1. add mineral oil in the oil tank, put the bleed screw in the thread and use PTFE pipe tape to fix it as answered above - dont know how effectively this way should be
2. bore the hole of the bleed screw port on the leaver and use a bolt with o-ring with bigger size -- also dont know if that a good way
3. change the leaver

A bit disappoint because of getting new bike with such small but possibly costly bug of the leaver. I will update the answer with my final solution later.

I have the same issue with shimano GRX 810 lever. firstly, determine whether issue is lever or screw. Does the funnel adapter still screw in? if yes, you may have to butcher an adapter then use a bung in its fill hole, after all the the bleed screw in effect is only a removable bung. you may be able to tap a thread for a nylon bolt etc into the butchered funnel adapter. If the issue is with the screw replace with part no Y0C698030 from sjs cycles. Alternatively you could try a tiny dental band on the screw thread to help form a seal in the lever hole effectively rendering it a bung & not a screw.