Joe Easton's mod unfortunately hasn't been updated in a while.
Luckily, with a few changes, you can get it working on 3.10
Follow @djspiros2012's post to get it working on 3.9: https://community.native-instruments.com/discussion/comment/61817/#Comment_61817
Then in C:\Program Files\Native Instruments\Traktor Pro 3\Resources64\qml\Screens\S4MK3\Screen.qml under
Item {
id: screen
change
property bool isLeftScreen: true
to
property int side: ScreenSide.Left;
readonly property bool isLeftScreen: (screen.side == ScreenSide.Left)
3.9 needed a lot of changes due to the update to Qt, but 3.10 just seemed to break the right screen, which the above fixes.