The default KDE wacom setting is that the pen cursor follows the "active screen".
That means that if you're using the pen as your pointing device, to click on something on another monitor you have to somehow click somewhere in the other monitor to make it "active", and only then can you use the pen. This means you have to grab a mouse or use another pointing device every time you move the cursor from one screen to another. This is so klunky as to be almost totally unusable. The only other option in the KDE Graphics Tablet settings is to map it to only one of the screens.
Is there a way to configure it to map across both screens, like you can with Gnome and other DEs or indeed Windows or Mac?