According to Optical limits (Photozone), the DA 35 2.4 and DA 70 are the sharpest,
I'd also point out more than a few of the lenses you own are listed as having excellent sharpness.
I suspect your issue is lens calibration.
I look at your list and what you don't know about your lenses stands out.
The 18-135 stacks up nicely at 24mm, with any Pentax lens at that focal length, and that extends it's excellent rating right to 135mm for the centre sharpness.
Your 35 2.4 tends to be a little clinical, but doesn't have a sharpness issue.
Your preference for your 100 macro suggests you like lenses that lack distortion and are constantly sharp edge to edge. Others who are suggesting macros, are right on point. I personally own the FA 50, Sigma 70 , Tamron 90 and DFA 100. There are lots to choose from.
The philosophy found in many Pentax lenses "lens for the way people take pictures, not for the test charts" definitely doesn't appeal to your sensibilities. The problem for you being apart from the macros, Pentax didn't in the past make a lot of lenses that suit your preferences. Any of the new DFAs should work for you though. Another that might work would be the DA*60-250.
Optical limits will give you good info on the older lenses if you're interested.
Pentax K Lens Tests
You'll find some of the lenses you can't live with are very highly rated, at 16 MP and 10 MP.