I would use a painted shader (set to 3D) to designate the area you want to glyphs in, use it to mask a surface shader where the glyph image map is sitting on as displacement or a child. Or a PF masking and hit seed until you're satisfied with a random set of glyphs.
I would also blur the image map a bit in PS or so, and use breakup (not just color) in the said surface layer to crumble the outlines a bit where it displaces inward.
You can also use the glyph to mask some darker tint in (or lighter, or an actual color if you prefer), just add a color adjust on the same surface layer as child. If you want that to be randomly variable, add another surface layer first as child and have the color adjust sit on that. You can then use an additional PF to mask the extra surface layer.