The spanner nuts will clean (restore) the threads once thru the rough area once or twice. You need to lube the threads while doing this. A small jeweler file (triangle shape) will clean up deformities. A Mallet and an old flat-tip screwdriver or a bronze punch will coax the nut thru those areas.
If you have a metric Tap and Die set the included thread pitch gage will tell you the pitch per mm and you can purchase a thread file like this.
https://www.amazon.com/Allstar-Perfo.../dp/B003BZLK6O
However you mentioned a fully adjustable KW suspension. Is that new shocks or rear coilovers, ditching the current rear springs and perches?