senshu Hey, sorry for answering so late, I've been terribly busy (I live in Northern Italy and you can guess the rest).
I actually solved the problem, and I thought I had deleted the post so as not to cause any confusion, guess I failed to do that lol. Basically what happened was that I created the text layers in Inkscape with the wrong tool and Sozi couldn't recognize them. I experimented a bit and discovered the solution.
Thanks for your patience,