Discovering the solution I feel a bit like a *****.
The output channels, just as the input channels are stereo.
So ...
Ch1 L in (Cakewalk Track1 Panned Left) > Touchmix Ch1 Out = Touchmix Ch1
Ch1 R in (Cakewalk Track2 Panned Right) > Touchmix Ch1 Out = Touchmix Ch2
Kinda obvious after thinking about it …