Wow I can't fathom the amount of work that has gone into this project. Was the multi-line editor a challenge? I know SVG Edit has been struggling with this feature for some time.
We ended up using foreignObject for rendering text, with the compromise that we need to look for solutions to enable pure svg export. This is still a technical debt on our plate. A roundtrip solution that converts hybrid SVG into PostScript and then back into SVG may work... we'll see.
Either way, we'll start writing some technical articles on our blog, so others can take advantage of our findings (we really owe a LOT to the community)