You need to use a text editor to fix this.
Do this:
- Save file as Inkscape-SVG
- Open file with text editor (e.g. notepad++)
- search for all occurrances of <tspan
- replace them with <tspan sodipodi:role="line"
(make sure there is a space before the next word in the SVG)
- Save.
I think the problem was that this file has somewhere in between not been saved as Inkscape SVG, which has removed that 'sodipodi:role' item. I think this is a bug (that it's not restored, when the file is loaded). But it's possible to fix for your file.
Hope it works out!