Getting a touchscreen working

I'm trying to get a multitouch Planar PCT2235, listed in xinput as a "Weida Hi-Tech CoolTouchR System", working well on Manjaro KDE. It does work as a basic mouse (one point of clicking, moves the cursor wherever I touch), but not working with multitouch. I know the system is, on some level, taking in the multitouch events as I can pinch to zoom, use two fingers to scroll, etc in Chromium. More dedicated touchpad specific solutions like Fusuma and libinput-qt don't seem to recognize the device at all. On windows, the device doesn't even interrupt the regular mouse to use, which I'd like but don't need if that bit isn't doable.

There are some older threads on the topic that seem to end on using "touchegg-qt5" to handle multitouch events, but this package no longer builds thanks to some changes in the makedeps, and binaries seem to have been dropped from every user repository I can find.

Forum kindly sponsored by