Re-answering this issue … I guess Guru uses a “bridge code” to be able to create easy templates for controls to appear depending on the hardware device to be controlled.
But the basis is the same. It use the API to define the controls (the sliders in this case), and it is not possible to define it in another way. I suppose that through the external script (template) it will not be possible to modify anything. It would be necessary to modify the Guru code base in order to modify some properties of the slider bar.
As I said before, regardless of their size, the only advanced thing available for a sliding bar is to play with the minimum and maximum values, turning them into variables.
It is not possible to do anything else. There is not even a property to properly convert a sliding bar for panning.
Anyway, I don’t know what you mean by “more advanced.” The only useful thing is to play with the values of the MIDI input to change the behavior in the physical control. For example, instead of jump 1 value, jump 10 values in relative mapping. Things like that.
In this case, it is almost better to build a new tool on purpose for each hardware device. There would be much more control (more specific).