So I decided to buy another Tbook 16 Pro keyboard and guess what? The trackpad works fine in Android on the same tablet (E5C8)! While the keyboard looks identical to the original (can’t find ANY differences whatsoever), it’s actually a different keyboard (identifies differently in Android) – and it actually seems a little cheaper (more flex when typing, etc) – but it works… Strange….
The new keyboard is identified as “EBITS-EB_WIN11_4-US-A1-16-00 USB Keyboard” in Androids “Language and Input” settings (instead of simply “HID 1018:1006” like the other keyboard).
Just an FYI in case anyone else runs into the same thing…