Please help.
So I've done a bunch of testing on other systems and configurations. There is an inherent problem with the way Windows handles touch/pen input. Though there is clearly a way for developers to get around it, this really shouldn't be a stumbling block at the OS level in the first place.
I've created an issue with MS feedback and hopefully we can get some upvotes on that issue in the hopes of getting it fixed. Please see here if you have the time and care about this. These votes issues do sometimes get addressed:
https://aka.ms/AAa1dta
To summarize :
Performing a click-drag action with a stylus or touch does not register (as a click nor a click-drag) until a certain "deadzone" of movement is surpassed. This causes a complete inability for small and accurate adjustments. So no ability to make the subtle adjustments we need. And no way to go into touch automation parameters on anything. This also eliminates the ability to simply touch and hold a GUI object since the click does not register as a click until release. Again, an issue for writing touch automation.
The OS GUI overlay clearly recognize the inputs and immediate movement. Unfortunately they do not pass that on to the underlying program, instead imposing this "deadzone" behaviour. There's also evidence that the OS even makes exemptions on this for itself since it's obviously not desirable in instances where accurate manipulation is necessary. For example: dragging a slider in the Sound settings panel reacts immediately. Test show this may be tied to Windows Ink.
This behaviour needs to be removed or made globally optional for many programs to work as intended.
Maybe Cockos can tie into the API/Library/whatever to make this work regardless though (as others seem to be able to) since I'm not holding my breath with MS development.