You've caught me at a bad time, unable to check my notes.

Hyperlinking behaves differently in html, Plucker and FB2 files, at least within FBReader. But if I recall correctly (and I'll come back and correct myself if I misstate things now), in the html file you have to use the name attribute -- and not the id attribute -- to identify the linked-to anchor.

And I think I got it to work by putting an actual <a> tag there, and not just putting a name attribute on some other tag.