By George, I’VE GOT IT!!! 
The culprit was the setting “WinTab” under Configure Krita > Tablet Settings. Just switched to “Windows 8+ Pointer Input (Windows Ink)” at a whim, did a re-start - and my strokes are smooth and fading and whatnot as can be!!!
Here’s the proof:
@Michelist @AhabGreybeard @Voronwe13
Thank you so much for going beyond your limits to help me out! You guys are stunners! 