Not a complete list, but rather what I have installed on my system ls /usr/bin/*5 -1:
/usr/bin/checkXML5
/usr/bin/kbuildsycoca5
/usr/bin/kcmshell5
/usr/bin/kcookiejar5
/usr/bin/kded5
/usr/bin/kglobalaccel5
/usr/bin/kiconfinder5
/usr/bin/kioclient5
/usr/bin/kpackagetool5
/usr/bin/kquitapp5
/usr/bin/kreadconfig5
/usr/bin/ktelnetservice5
/usr/bin/ktrash5
/usr/bin/kwalletd5
/usr/bin/kwriteconfig5
/usr/bin/meinproc5
/usr/bin/preparetips5
/usr/bin/solid-hardware5
/usr/bin/kjs5 (kjs)
kinit:
/usr/bin/kdeinit5
/usr/bin/kshell5
/usr/bin/kwrapper5
/usr/bin/kdebugdialog5 (kdelibs4support)
/usr/bin/systemsettings5
kde-cli-tools:
/usr/bin/ktraderclient5
/usr/bin/kmimetypefinder5
/usr/bin/keditfiletype5
/usr/bin/kdemv5
/usr/bin/kde-open5
/usr/bin/kdecp5
/usr/bin/kstart5
/usr/bin/ksvgtopng5
kwalletmanager:
/usr/bin/kwalletmanager5