The moon medallions are gorgeous ! I should definitely get some as presents.
Looks like the "one ring" received a very deep and good polishing !
Although I have no idea what this 0.001 mm technique is, judging from the 3d preview the model is actually quite facetted/low-poly ?
I see nothing wihich should prevent stairstepping, other then the post processing polshing ?
Also, the letters seem awfully thin, this could lead to stuck powder left during the green phase, which probably fused during the oven cycle.
Making the letters less pronounced. Combined with a smooth polishing this seems to have leveled it out almost completely.
I doubt poking at it now would have much effect, although you might be able to re-engrave it a little.
Probably should make the letters thicker and add a chamfer/tapering, so the powder can get out more easily.
If you make them even thicker, you could add a red baking dye/paint in the crevices, like in the blog post.