KMail (and gpgol in the upcoming no-mime branch) call
kleopatra --query <fingerprint>
to show the details of a key.
This command either shows the details of a key if the key is available locally
or starts a keyserver search if it is not available.
As there is no such command in GPA i'm currently showing the message box:
"Could not find Kleopatra. Please reinstall Gpg4win with the Kleopatra component
enabled."
When someone clicks on key details in GpgOL and Kleopatra is not found.