With the latest iPadOS, using a mouse and trackpad works really nicely in general.
In Cubasis 3 what I notice is that the 2 finger scrolling with the Apple Magic Trackpad 2 does not work like in other apps such as Safari etc. it would be super efficient if full support for this device would be available in Cubasis 3. Similarly with my Logitech mouse the scroll wheel doesn’t work. So it seems that in general scrolling is not supported in Cubasis 3?