> The library seems to use BibLatex, which is pretty standard. No reference managers I know understands the above HTML.

It should be easy to write some once-and-for-all XSLT (or other processor, that's just what I'm used to for XML, but I don't know what's easy to call from JS) to transform well-formed HTML as above to a format that BibLaTeX understands. Since it'd be a one-size-fits-all transformer, anyone who wants to write the HTML can do so.