/usr/include/KF5/templateparser/ is in libkf5templateparser-dev 4:16.04.3-3~deb9u1.
This file is owned by root:root, with mode 0o755.
..
/usr/include/KF5/templateparser/customtemplates.h
/usr/include/KF5/templateparser/customtemplates_kfg.h
/usr/include/KF5/templateparser/customtemplatesmenu.h
/usr/include/KF5/templateparser/defaulttemplates.h
/usr/include/KF5/templateparser/globalsettings_templateparser.h
/usr/include/KF5/templateparser/templateparser.h
/usr/include/KF5/templateparser/templateparser_export.h
/usr/include/KF5/templateparser/templatesconfiguration.h
/usr/include/KF5/templateparser/templatesconfiguration_kfg.h
/usr/include/KF5/templateparser/templatesinsertcommand.h
/usr/include/KF5/templateparser/templatestextedit.h
/usr/include/KF5/templateparser/templatesutil.h
/usr/include/KF5/templateparser/ui_templatesconfiguration_base.h