The KCM touchpad module, while it has very good defaults, currently misses the fine-grained configuration that was present for synaptics touchpads in the plasma 5 KCM in order to get most out of my touchpad's capabilities. The pointer speed and the sensitivity configuration and the coasting and circular scrolling features are what I miss the most.
The KCM is a simple GUI frontend to let you configure the settings exposed by the backend. It can't add configurability for features the backend doesn't have. The Libinput backend has fewer features compared to the Synaptics backend, so the KCM exposes fewer configuration knobs. There isn't anything KDE can do about this, I'm afraid.
Ok, thanks for the clarification! So I'd have to file that against libinput before the KCM could freeze anything in that regard.
*** Bug 498979 has been marked as a duplicate of this bug. ***