I suspect it will make TIG welding in the future somewhat of a challenge.......
That was my thought. If you or anyone else ever decided to TIG weld the heads and redress and cut new slots, contamination from any residual solder could be a problem.
The burrs around the screw slots in the before photos looked as if they could have been improved a lot by peening the displaced metal back toward the slot, and then dressing with a screw slot file. Doing this requires removing the screw, clamping it in lead padded vise jaws to protect the threads, and very carefully using a small hammer and punch to peen the metal back in place. Naturally, this may not be worth the time if you can simply find a correct replacement screw.