kcms/launch/kcm_launchfeedback.desktop
X-DocPath=kcontrol/kcmlaunchfeedback/index.html
doc/kcontrol/kcmlaunch/CMakeLists.txt
kdoctools_create_handbook(index.docbook INSTALL_DESTINATION ${KDE_INSTALL_DOCBUNDLEDIR}/en SUBDIR kcontrol/kcmlaunch)
kcmlaunch != kcmlaunchfeedback therefore the en_US documentation is not found
Scripty generates the install path from the dir name
l10n-kf5/[lang]/docs/kde-workspace/kcontrol/kcmlaunch/CMakeLists.txt
kdoctools_create_handbook(index.docbook INSTALL_DESTINATION ${HTML_INSTALL_DIR}/${CURRENT_LANG}/ SUBDIR kcontrol/kcmlaunch )
We need X-DocPath=kcontrol/kcmlaunch/index.html in the desktop file
then khelpcenter finds the correct docbook for en_US and all language translations