The "numpad" paging keys are very special and should not be used as clickable targets; this would be too confusing.
However, in the next version (>1.22), the cursor shortcuts will be fully editable in the preferences, including page left/right

Moreover, there will be new targets for the skin as "workspacepageleft", "workspacepageright" and so on.
Best regards,
Your Silverjuke Team