I think the built-in OTF support for contextual alternates still go by character pairs, so na na na will still look identical even if I can get ba na na to look slightly different. I can easily get SVG out of FontForge, though, and I've come across some programs that take text, randomize the glyphs used, and return an SVG. I might be able to figure out something like that. I probably won't go to that extent on my blog, but it may be fun to explore just for curiosity's sake