I cannot completely resolve the problem.
- camera recognition
As ART display RICOH as camera maker using exiv2, in the file slr-pentax.xml, replace Pentax by RICOH:
<camera>
<maker>RICOH</maker>
<model>Pentax KP</model>
<model lang="en">KP</model>
<mount>Pentax KAF2</mount>
<cropfactor>1.534</cropfactor>
</camera>
This modification should be propagated upstream in the lensfun github repo.
- for the lens, I cannot answer