I'm dyslexic and can't possibly read a post that long.
You have likely bent the slide stop spring during reassembly.
It's easy to bend, especially when new, and easy to fix.
You can order some springs from the Kahr web site.
And you'll need one of those torx thingies (I think it's #8 or #9?).
You have to be very careful, especially when tight and new,
inserting the slide stop into the frame.
Insert at about 4 o'clock part way in.
Move slide to the correct spot.
Then rotate the slide stop to 3 o'clock.
And carefully push the rest of the way in.
I did the same thing.
BTW my MK40 Elite got much better at 200+.
But wasn't 100% reliable until 400+.
At that point she will feed anything and runs like glass.
MK40's are fine weapons once you get past the break in.
And master the re-assembly procedure.
BTW KahrTalk.com forum is a great place to resolve Kahr related issues.