Hello Scott,
For the Launchpad models for which Hauptwerk currently (v5 and v6: viewtopic.php?f=3&t=19704#p147751 ) has full native support, i.e. the 'Novation Launchpad Mk2' and the original (mark 1) 'Novation Launchpad', yes -- Hauptwerk can use and control the sixteen round buttons in the same way as any of the square buttons.