I have not been following this thread very well and I may be misunderstanding the issue.
Nevertheless, what happens if you convert your SVG to raster and then use IM annotate (label, caption, pango, draw, etc) to insert the text right on the raster image? Can you do that? see http://www.imagemagick.org/Usage/text/
Can you convert your original SVG to raster or does that fail as well?