It seems I do more typing than the good folks at Kinesis expected:
In round numbers, the keyboard is all of two years old and that little ridge is pretty much history.
The ultimate fix will likely involve a dab of epoxy, but a duct tape snippet should show me how much of a bump my fingers need to find the home keys without conscious thought:
Early returns suggest one layer isn’t quite prominent enough; some iteration will be in order.
And, yeah, I should yank the keycaps for some deep cleaning.
The Smell of Molten Projects in the Morning 
HP keyboard my company provided 13 years ago is still going strong in that regard. It’s part disgusting, part worn to high shine, but bumps are still very prominent :)
The bumps on my ancient Maxi-switch (ca. 30 years) are still fine. It also has double injection molded key caps so the letters are still perfect. Although it has the same problem of collecting dust and crud.
Today’s bespoke mechanical keyboards (seem to) all have decal, rather than double-shot, keycaps. Maybe we’re supposed replace the caps every few years?