Hi Martin -- We'll look into this.
To make sure we understand -- is it only an issue for you with horizontal scrolling (column to column) or also vertical scrolling (row to row)? When you say touch-based, do you mean clicking on the scroll bar, or not on the scroll bar but rather using a wheel/two-finger swipe on the trackpad?
Are you using molecular data or other categorical data?
We use the matrix editor all the time with our own data, and haven't hit this problem yet, except that that we mourn the loss of single-column/row scroll arrows in the scroll bars, which Apple removed back in 2010.
Best wishes,
Wayne