Right, it’s not actually supported in MIDI spec.
Your DAW is what receives these relative changes to map and sent out to your synth as absolute values, check out 27.2.4 Mapping to Relative MIDI Controllers.
I’m fairly certain that it’d be a requirement for any “endless” encoder, and it makes less sense in implementation to include relative values for the Touche which has a limited travel and is easier to track and bound the absolute value of than a knob without any stopping points.
That relative incrementation of the Goliath is required by design of the encoder but does not appear to be any special “mode”.
Is this nitpicky? Absoutely!
It was a good opportunity for me to look up what you were talking about and understand my hardware and the ecosystem a bit better 
There’s a valid conceptual difference between the method of input, whereas a free turning encoder has no default state the Touche will return itself to its calibrated zero through mechanical means, there’s no need to push relative values. So even If there was a physical “hold” or it had no spring-back, there would still be physical bounds of travel.
Considering the mouse-like design of the Touche, i wonder if you might be looking for a combination of a trackball and max patch for those needs? I’m sure someone’s coded that up already and through scale of industry it’d be a $30 instead of $300 2 axis input device.